3-hydroxyisobutyryl-CoA hydrolase deficiency

Mendelian MONDO:0009603 Pathograph 19 Show in embeddings browser hereditary disease inborn error of metabolism

3-hydroxyisobutyryl-CoA hydrolase (HIBCH) deficiency is an autosomal recessive disorder of mitochondrial valine catabolism caused by biallelic pathogenic HIBCH variants. The clinical spectrum ranges from severe neonatal or infantile neurodegeneration with metabolic decompensation and Leigh-like basal-ganglia injury to later-onset progressive movement disorder.

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1
Mappings
1
Inheritance
6
Pathophys.
16
Phenotypes
2
Hypotheses
4
Gaps
19
Pathograph
1
Genes
4
Medical Actions
3
Subtypes
4
Differentials
11
References
2
Deep Research
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Mappings

MONDO
MONDO:0009603 3-hydroxyisobutyryl-CoA hydrolase deficiency
skos:exactMatch MONDO
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Inheritance

1
Autosomal Recessive HP:0000007
Autosomal recessive inheritance
Show evidence (2 references)
DOI:10.1159/000508728 SUPPORT Human Clinical
"3-hydroxyisobutyryl-CoA hydrolase (HIBCH) deficiency (OMIM 250620) is an autosomal recessive inborn error of valine catabolism"
The clinical review explicitly identifies autosomal recessive inheritance.
"HIBCH | HGNC:4908 | 3-hydroxyisobutyryl-CoA hydrolase deficiency | MONDO:0009603 | AR | Definitive"
ClinGen records autosomal recessive inheritance for the definitive gene-disease relationship.

Subtypes

3
Neonatal onset
The least frequent and generally most severe presentation, beginning at birth with feeding difficulty, tone abnormality, and seizures.
Infantile onset
The most common presentation, beginning in the first two years with neurodevelopmental delay or regression, hypotonia, movement disorder, and episodic neurologic deterioration.
Late onset
A childhood-onset, more slowly progressive presentation dominated by movement disorder, sometimes paroxysmal dystonia, and variable cognitive impairment.

Mechanistic Hypotheses

2
Canonical HIBCH Reactive-Metabolite Model
canonical_hibch_reactive_metabolite_model CANONICAL
Evidence balance 2 support
Loss of HIBCH activity blocks hydrolysis of 3-hydroxyisobutyryl-CoA. Accumulated valine-pathway intermediates are associated with 3-hydroxyisobutyrylcarnitine and methacrylyl-CoA-derived thiol conjugates. Reactive intermediate toxicity is proposed to impair mitochondrial proteins and energy metabolism, but the causal steps and the reason for selective basal-ganglia vulnerability are not fully established in humans.
Show evidence (2 references)
PMID:26163321 SUPPORT Human Clinical
"Urine metabolite investigations also showed increases in 3-hydroxyisobutyryl carnitine, 2,3-dihydroxy-2-methylbutyrate and several metabolites indicating accumulation and subsequent metabolism of methacrylyl-CoA and acryloyl-CoA."
Human metabolite studies support accumulation of valine-derived intermediates.
PMID:24299452 SUPPORT Human Clinical
"The index case had deficiencies of multiple RC enzymes and PDHc in skeletal muscle and fibroblasts respectively, but these were normal in his younger brother."
Human secondary mitochondrial abnormalities support part of the model but their sibling discordance shows that they are not required.
Emerging Lysine Methacrylation Model
emerging_hibch_lysine_methacrylation_model EMERGING
Evidence balance 2 support
Cell, patient-fibroblast, and Drosophila experiments implicate ectopic protein lysine methacrylation in mitochondrial morphology and respiratory defects. This is an emerging preclinical mechanism and does not establish a human therapy.
Show evidence (2 references)
PMID:40056416 SUPPORT In Vitro
"Fibroblasts from patients with HIBCH or ECHS1 mutations show similar mitochondrial changes and elevated Kmea, which are significantly reversed by administering N-acetyl-L-cysteine to reduce Kmea levels."
Patient fibroblasts support an in-vitro methacrylation phenotype and experimental rescue.
PMID:40056416 SUPPORT Model Organism
"Reducing Kmea modification partially rescues mitochondrial morphology changes in cells and eye degeneration in flies."
Rescue in flies is preclinical and cannot be interpreted as clinical efficacy.
?

Discussions and Knowledge Gaps

4
Which methacrylyl-CoA-derived protein modifications drive human neural injury, and why are secondary PDH and respiratory-chain defects variable?
KNOWLEDGE GAP OPEN gap_hibch_reactive_metabolite_mechanism
Human metabolites support reactive-intermediate accumulation, but thiol adduction, glutathione depletion, lysine methacrylation, mitochondrial dysfunction, and selective basal-ganglia vulnerability have not been joined into a validated human causal chain.
Show evidence (2 references)
PMID:24299452 SUPPORT Human Clinical
"The index case had deficiencies of multiple RC enzymes and PDHc in skeletal muscle and fibroblasts respectively, but these were normal in his younger brother."
Affected siblings demonstrate variable secondary mitochondrial findings.
PMID:40056416 SUPPORT In Vitro
"We propose that ectopic Kmea modification mediates the defects caused by HIBCH- or ECHS1-deficiency."
The newest methacrylation model remains an experimental proposal.
What valine targets, age at initiation, monitoring strategy, and nutritional safeguards provide meaningful long-term clinical benefit?
KNOWLEDGE GAP OPEN gap_hibch_valine_restriction
Valine restriction is mechanism-directed and recommended by experts, but published outcomes are uncontrolled, regimens vary, and natural history is heterogeneous.
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"There is currently no consensus on HIBCH deficiency treatment approaches."
The cohort review directly identifies the sparse and heterogeneous treatment evidence.
Can isomer-resolved C4-OH, SCPC/SCPCM species, or a combined panel achieve adequate sensitivity and specificity for diagnosis or newborn screening?
KNOWLEDGE GAP OPEN gap_hibch_biomarker_and_screening_validation
C4-OH is neither universal nor specific without isomer separation, while promising thiol-conjugate markers have very small selected denominators and require specialized methods. Screening thresholds and clinical benefit are not validated.
Show evidence (2 references)
PMID:26163321 SUPPORT Human Clinical
"Increased hydroxy-C4 carnitine is therefore not specific for HIBCHD"
The paper identifies both the limitation and a candidate combined approach.
PMID:33762937 SUPPORT Human Clinical
"SCPCM seems to be more speci fic for disease diagnosis, but more samples are needed for verification."
The clinical series explicitly calls for more marker validation.
Can variant position or residual HIBCH activity reliably predict severity and survival?
INTERPRETATION OPEN interpretation_hibch_variant_location_survival
A combined ECHS1/HIBCH natural-history analysis reported a survival association with HIBCH variant location, but the ultra-rare sample and retrospective ascertainment do not support deterministic counseling.
Show evidence (1 reference)
DOI:10.1002/jimd.12288 SUPPORT Human Clinical
"Among all 89 cases, we observed a longer survival in HIBCH compared to SCEH patients, and in HIBCH patients carrying homozygous mutations on the protein surface compared to those with variants inside/near the catalytic region."
The study reports an exploratory variant-location survival association.

Pathophysiology

6
HIBCH catalytic loss
Biallelic pathogenic HIBCH variants reduce mitochondrial 3-hydroxyisobutyryl-CoA hydrolase activity, establishing the initiating enzymatic lesion.
HIBCH hgnc:4908 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves HIBCH (hgnc:4908). hgnc:4908 is a gene from the HUGO Gene Nomenclature Committee.
3-hydroxyisobutyryl-CoA hydrolase activity GO:0003860 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased 3-hydroxyisobutyryl-CoA hydrolase activity (GO:0003860). GO:0003860 is a molecular function from the Gene Ontology. ↓ DECREASED
mitochondrial matrix GO:0005759 Gene Ontology (GO) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in mitochondrial matrix (GO:0005759). GO:0005759 is an anatomical location from the Gene Ontology.
Show evidence (2 references)
PMID:24299452 SUPPORT In Vitro
"Fibroblast HIBCH activity was below detectable limits in both patients"
Enzyme assay demonstrated absent detectable activity in fibroblasts from two affected siblings.
"HIBCH | HGNC:4908 | 3-hydroxyisobutyryl-CoA hydrolase deficiency | MONDO:0009603 | AR | Definitive"
ClinGen classifies the HIBCH-disease relationship as definitive.
Impaired 3-hydroxyisobutyryl-CoA hydrolysis
Failure to convert 3-hydroxyisobutyryl-CoA to free 3-hydroxyisobutyrate disrupts mitochondrial valine catabolism.
valine catabolic process GO:0006574 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased valine catabolic process, annotated with L-valine catabolic process (GO:0006574). GO:0006574 is a biological process from the Gene Ontology. ↓ DECREASED
mitochondrial matrix GO:0005759 Gene Ontology (GO) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in mitochondrial matrix (GO:0005759). GO:0005759 is an anatomical location from the Gene Ontology.
Show evidence (1 reference)
PMID:26163321 SUPPORT Other
"conversion of 3-hydroxyisobutyryl-CoA to free 3-hydroxyisobutyrate"
This defines the blocked reaction.
Reactive valine-derived intermediate accumulation
Methacrylyl-CoA and related electrophilic intermediates can react with sulfhydryl-containing molecules. SCPC, SCPCM, their derivatives, and other urine metabolites report this biochemical state; their contribution to neural injury remains incompletely defined.
mitochondrial matrix GO:0005759 Gene Ontology (GO) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in mitochondrial matrix (GO:0005759). GO:0005759 is an anatomical location from the Gene Ontology.
Show evidence (1 reference)
PMID:26163321 SUPPORT Other
"Urine tandem mass spectrometry screening showed large increases in the cysteine conjugate of methacrylate previously described in HIBCHD."
The biochemical reactivity of methacrylyl-CoA supports the toxicity model.
Variable secondary PDH and respiratory-chain dysfunction
Secondary pyruvate-dehydrogenase-complex and respiratory-chain abnormalities occur in some patients, but are neither universal nor a required bottleneck for the neurologic phenotype.
oxidative phosphorylation GO:0006119 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased oxidative phosphorylation (GO:0006119). GO:0006119 is a biological process from the Gene Ontology. ↓ DECREASED
mitochondrion GO:0005739 Gene Ontology (GO) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in mitochondrion (GO:0005739). GO:0005739 is an anatomical location from the Gene Ontology.
Show evidence (2 references)
PMID:24299452 SUPPORT Human Clinical
"The index case had deficiencies of multiple RC enzymes and PDHc in skeletal muscle and fibroblasts respectively, but these were normal in his younger brother."
Two similarly affected siblings demonstrate that the biochemical abnormality is variable.
"Biochemical profiling revealed elevated C4-OH acylcarnitine, with variable abnormalities in blood lactate, amino acids, and respiratory chain complexes."
The Bahrain cohort independently describes respiratory-chain abnormalities as variable.
Illness-associated acute neurometabolic decompensation
Intercurrent illness, fasting, or another catabolic stress can precipitate acute encephalopathy and neurologic deterioration on the background of disrupted valine metabolism.
Show evidence (2 references)
DOI:10.1159/000508728 SUPPORT Human Clinical
"recurrent metabolic attacks with intercurrent illness"
Illness-associated attacks are a documented part of the clinical course.
PMID:41264763 SUPPORT Other
"episodes of neurologic deterioration"
GeneReviews includes episodic deterioration in the common infantile presentation.
Leigh-like basal-ganglia neurometabolic injury
HIBCH deficiency commonly produces a Leigh-like syndrome with bilateral pallidal or broader basal-ganglia injury. The selective neuroanatomic vulnerability is observed consistently, but its molecular basis remains unresolved.
basal ganglion UBERON:0002420 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in basal ganglion (UBERON:0002420). UBERON:0002420 is an anatomical location from the Uberon multi-species anatomy ontology.
Show evidence (2 references)
PMID:33762937 SUPPORT Human Clinical
"Basal ganglia 8 (100%) 28 (93%) 36 (95%)"
Basal-ganglia involvement occurred in 36 of 38 pooled, largely Leigh-spectrum cases with imaging data.
PMID:24299452 SUPPORT Human Clinical
"Two brothers born to distantly related Pakistani parents presenting in early infancy with a progressive neurodegenerative disorder, associated with basal ganglia changes on brain magnetic resonance imaging"
The sibling report establishes the Leigh-like clinical-imaging presentation.

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for 3-hydroxyisobutyryl-CoA hydrolase deficiency Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.

Phenotypes

16
Digestive 2
Feeding difficulties FREQUENT HP:0011968 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Feeding difficulties (HP:0011968). HP:0011968 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Feeding dif ficulties 5 (63%) 14 (47%) 19 (50%)"
The pooled case table places feeding difficulty in the FREQUENT band.
Vomiting HP:0002013 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Vomiting (HP:0002013). HP:0002013 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:41264763 SUPPORT Other
"Infantile onset is the most common phenotype, presenting in the first two years of life with feeding difficulties, vomiting, developmental delay with regression"
GeneReviews includes vomiting in the infantile phenotype.
Eye 3
Nystagmus FREQUENT HP:0000639 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Nystagmus (HP:0000639). HP:0000639 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Nystagmus 3 (38%) 11 (37%) 14 (37%)"
The pooled case table places nystagmus in the FREQUENT band.
Strabismus OCCASIONAL HP:0000486 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Strabismus (HP:0000486). HP:0000486 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Strabismus 4 (50%) 6 (20%) 10 (26%)"
The pooled case table places strabismus in the OCCASIONAL band.
Optic atrophy OCCASIONAL HP:0000648 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Optic atrophy (HP:0000648). HP:0000648 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Optic atrophy 0 5 (17%) 5 (13%)"
The pooled case table places optic atrophy in the OCCASIONAL band.
Head and Neck 1
Microcephaly HP:0000252 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Microcephaly (HP:0000252). HP:0000252 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:41264763 SUPPORT Other
"movement disorder, microcephaly, vision impairment, and episodes of neurologic deterioration"
GeneReviews includes microcephaly in the infantile phenotype.
Musculoskeletal 2
Hypotonia FREQUENT HP:0001252 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypotonia (HP:0001252). HP:0001252 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Hypotonia 8 (100%) 20 (67%) 28 (74%)"
The pooled case table places hypotonia in the FREQUENT band.
Spasticity HP:0001257 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Spasticity (HP:0001257). HP:0001257 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
DOI:10.1038/s41439-023-00251-y SUPPORT Human Clinical
"the patient subsequently developed various new symptoms, including nystagmus, athetosis, and spastic paraparesis."
Longitudinal follow-up documents emergence of spastic paraparesis in an affected patient.
Nervous System 7
Global developmental delay FREQUENT HP:0001263 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Global developmental delay (HP:0001263). HP:0001263 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Developmental delay 5 (63%) 24 (80%) 29 (76%)"
The pooled case table places developmental delay in the FREQUENT band.
Developmental regression FREQUENT HP:0002376 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Developmental regression (HP:0002376). HP:0002376 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Developmental regression 7 (88%) 17 (57%) 24 (63%)"
The pooled case table places regression in the FREQUENT band.
Encephalopathy FREQUENT HP:0001298 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Encephalopathy (HP:0001298). HP:0001298 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Encephalopathy 6 (75%) 13 (43%) 19 (50%)"
The pooled case table places encephalopathy in the FREQUENT band.
Dystonia FREQUENT HP:0001332 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dystonia (HP:0001332). HP:0001332 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Dystonia 4 (50%) 15 (50%) 19 (50%)"
The pooled case table places dystonia in the FREQUENT band.
Ataxia FREQUENT HP:0001251 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Ataxia (HP:0001251). HP:0001251 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Ataxia 4 (50%) 11 (37%) 15 (40%)"
The pooled case table places ataxia in the FREQUENT band.
Seizure FREQUENT HP:0001250 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Seizure (HP:0001250). HP:0001250 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Seizures 3 (38%) 10 (33%) 13 (34%)"
The pooled case table places seizures in the FREQUENT band.
Cognitive impairment HP:0100543 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cognitive impairment (HP:0100543). HP:0100543 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:41264763 SUPPORT Other
"significant movement disorder with or without paroxysmal dystonia, variable cognitive impairment, and high survivability."
GeneReviews includes variable cognitive impairment in later-onset disease.
Growth 1
Failure to thrive HP:0001508 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Failure to thrive (HP:0001508). HP:0001508 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:41264763 SUPPORT Other
"individuals that survive typically have developmental delay, seizures, poor weight gain, and growth deficiency"
GeneReviews describes poor weight gain and growth deficiency among neonatal-onset survivors.
🧬

Genetic Associations

1
HIBCH pathogenic variants (Biallelic loss of function)
Gene: HIBCH hgnc:4908 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is HIBCH (hgnc:4908). hgnc:4908 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE variant_origin: GERMLINE
Autosomal Recessive
Show evidence (2 references)
PMID:41264763 SUPPORT Other
"The diagnosis of HIBCH deficiency is established in a proband with characteristic clinical, laboratory, and brain imaging findings and biallelic pathogenic variants in HIBCH identified by molecular genetic testing."
GeneReviews defines the biallelic molecular diagnostic requirement.
"HIBCH | HGNC:4908 | 3-hydroxyisobutyryl-CoA hydrolase deficiency | MONDO:0009603 | AR | Definitive"
ClinGen assigns definitive validity to this autosomal recessive gene-disease relationship.
💊

Medical Actions

4
Valine-restricted diet
Action: dietary interventionNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is dietary intervention (NCIT:C15447). NCIT:C15447 is a clinical intervention from the NCI Thesaurus. Ontology label: Dietary Intervention NCIT:C15447
Valine restriction is the expert-recommended targeted dietary approach, intended to reduce substrate flux into the impaired pathway. Evidence is limited to small uncontrolled reports and expert experience; no consensus protocol, controlled efficacy estimate, or universal age-specific valine target is established.
Mechanism Target:
INHIBITS Reactive valine-derived intermediate accumulation — Reduced valine intake is intended to decrease formation of reactive valine-derived intermediates.
Show evidence (1 reference)
PMID:41264763 SUPPORT Other
"MANAGEMENT: Targeted therapy: Valine-restricted diet."
GeneReviews identifies valine restriction as mechanism-targeted care.
Show evidence (2 references)
PMID:41264763 SUPPORT Other
"MANAGEMENT: Targeted therapy: Valine-restricted diet. As seen in other metabolic disorders, treatment using special formulas (medical food) can be implemented successfully via oral route in individuals diagnosed within the first few months of life."
GeneReviews describes practical implementation while not supplying a controlled efficacy estimate.
PMID:33762937 SUPPORT Human Clinical
"There is currently no consensus on HIBCH deficiency treatment approaches. A low-valine, carbohydrate-rich diet may be effective"
The clinical cohort explicitly identifies lack of consensus and uses cautious efficacy language.
Prevention of catabolism
Action: supportive careNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is supportive care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. Ontology label: Supportive Care NCIT:C15747
Avoidance of prolonged fasting and individualized sick-day planning are intended to reduce catabolic stress. Acute illness management should be directed by a metabolic specialist; the cached evidence does not define a validated universal emergency protocol.
Mechanism Target:
INHIBITS Illness-associated acute neurometabolic decompensation — Preventing catabolism is intended to reduce illness-associated decompensation risk.
Show evidence (1 reference)
PMID:41264763 SUPPORT Other
"prevent catabolism"
GeneReviews includes prevention of catabolism among management precautions.
Symptom-directed supportive care
Action: supportive careNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is supportive care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. Ontology label: Supportive Care NCIT:C15747
Multidisciplinary care addresses development, feeding, spasticity, epilepsy, movement disorder, vision, hearing, mobility, and family support. These interventions treat manifestations rather than the enzymatic defect.
Show evidence (1 reference)
PMID:41264763 SUPPORT Other
"Supportive care: Developmental and educational support; feeding therapy with gastrostomy tube as needed; standard treatments for spasticity and epilepsy; treatment of movement disorder per movement disorder specialist; management of ocular issues per ophthalmologist with low vision services as needed"
GeneReviews defines concrete multidisciplinary supportive care.
Avoidance of selected mitochondrial and dietary stressors
Action: medical action avoidanceNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is medical action avoidance, annotated with Lifestyle Therapy (NCIT:C15900). NCIT:C15900 is a clinical intervention from the NCI Thesaurus. Ontology label: Lifestyle Therapy NCIT:C15900
GeneReviews conditionally advises avoiding sodium valproate when possible because of secondary mitochondrial abnormalities, careful anesthesia use, and avoidance of prolonged propofol. It more directly advises against ketogenic or modified Atkins diets and lists triheptanoin as contraindicated; these are expert precautions rather than comparative-trial findings.
Show evidence (2 references)
PMID:41264763 SUPPORT Other
"Due to secondary mitochondrial abnormalities it may be beneficial to avoid sodium valproate if possible; consider anesthesia use carefully; avoid prolonged propofol use"
GeneReviews uses conditional wording for valproate and peri-anesthetic precautions.
PMID:41264763 SUPPORT Other
"ketogenic / modified Atkins diets should be avoided due to potential side effects; triheptanoin is contraindicated due to the potential increase in propionyl-CoA"
GeneReviews provides the stronger diet and triheptanoin avoidance language.
🔬

Biochemical Markers

6
3-hydroxyisobutyrylcarnitine (C4-OH) (INCREASED)
Context: Elevated blood C4-OH was reported in 20 of 31 tested pooled cases (65%). Specific measurement of 3-hydroxyisobutyrylcarnitine is more informative than a nonchromatographic aggregate C4-OH signal.
Pathograph Readouts
Readout Of Impaired 3-hydroxyisobutyryl-CoA hydrolysis Positive Diagnostic
Substrate-derived 3-hydroxyisobutyrylcarnitine reports the HIBCH hydrolysis block.
Show evidence (2 references)
PMID:33762937 SUPPORT Human Clinical
"Elevated blood C4-OH 5/8 (63%) 15/23 (65%) 20/31 (65%)"
The pooled table places elevated C4-OH in the FREQUENT band but shows it is not universal.
PMID:26163321 SUPPORT Human Clinical
"Increased hydroxy-C4 carnitine is therefore not specific for HIBCHD"
The study directly identifies isomeric interference and limited specificity.
Urinary 2,3-dihydroxy-2-methylbutyrate (INCREASED)
Context: Elevated in 8 of 15 tested pooled cases (53%).
Pathograph Readouts
Readout Of Reactive valine-derived intermediate accumulation Positive Diagnostic
This urine metabolite is associated with reactive valine/propionate-pathway intermediates but is not HIBCH-specific.
Show evidence (2 references)
PMID:33762937 SUPPORT Human Clinical
"Elevated urine 23HD2MB 6/7 (86%) 2/8 (25%) 8/15 (53%)"
The pooled table places this metabolite in the FREQUENT band with a small denominator.
PMID:26163321 SUPPORT Human Clinical
"Patients with propionic acidaemia were investigated and found to have increased urine levels of 23DH2MB"
Its occurrence in propionic acidemia limits specificity.
Urinary S-(2-carboxypropyl)cysteine and its carnitine ester (INCREASED)
Context: SCPC and its carnitine ester are specialized urine markers not captured by routine organic-acid or acylcarnitine testing.
Pathograph Readouts
Readout Of Reactive valine-derived intermediate accumulation Positive Diagnostic
SCPC species report conjugation of reactive methacrylyl-derived intermediates.
Show evidence (2 references)
PMID:26163321 SUPPORT Human Clinical
"Semi-quantitative urine screening by tandem mass spectrometry revealed increased excretion of SCPC in samples from the HIBCHD and SCEHD patients (Fig. 2A)."
Specialized urine tandem mass spectrometry detected SCPC in HIBCH and ECHS1 deficiency.
PMID:26163321 SUPPORT Human Clinical
"the carnitine ester of SCPC were also found in the HIBCHD and SCEHD patients."
The same study identifies the SCPC carnitine ester as a related marker.
Urinary S-(2-carboxypropyl)cysteamine (INCREASED)
Context: SCPCM was elevated in all five selected published cases in which it was measured; this tiny, selected denominator must not be interpreted as 100% clinical sensitivity.
Pathograph Readouts
Readout Of Reactive valine-derived intermediate accumulation Positive Diagnostic
SCPCM is a methacrylyl-CoA-derived thiol conjugate.
Show evidence (2 references)
PMID:33762937 SUPPORT Human Clinical
"Elevated urine SCPCM 3/3 (100%) 2/2 (100%) 5/5 (100%)"
The pooled table reports five positive selected tests, not population-level sensitivity.
PMID:33762937 SUPPORT Human Clinical
"SCPCM seems to be more speci fic for disease diagnosis, but more samples are needed for verification."
The authors explicitly qualify the marker as requiring further validation.
Blood lactate (Variable)
Context: Blood lactate was elevated in 15 of 35 tested pooled cases (43%); normal lactate therefore does not exclude HIBCH deficiency.
Pathograph Readouts
Readout Of Variable secondary PDH and respiratory-chain dysfunction Positive Diagnostic
Elevated lactate is a nonspecific, inconsistent marker of secondary energy-metabolism dysfunction.
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Increased blood lactate level 3/8 (38%) 12/27 (44%) 15/35 (43%)"
The pooled table places elevated lactate in the FREQUENT band while demonstrating variability.
HIBCH activity in cultured skin fibroblasts (DECREASED)
Context: Activity was decreased in all 11 selected published cases with reported fibroblast testing; this is an assay result in a small, clinically selected denominator.
Pathograph Readouts
Readout Of HIBCH catalytic loss Negative Diagnostic
Reduced enzyme activity directly measures the initiating catalytic defect.
Show evidence (2 references)
PMID:33762937 SUPPORT Human Clinical
"Decreased HIBCH activity in skin fibroblasts — 11/11 (100%) 11/11 (100%)"
The pooled table reports decreased activity in all 11 tested published cases.
PMID:24299452 SUPPORT In Vitro
"Fibroblast HIBCH activity was below detectable limits in both patients"
Direct enzyme testing confirmed absent detectable activity in affected siblings.
🔬

Diagnosis

4
Molecular genetic confirmation
The diagnosis is established by identifying biallelic pathogenic or likely pathogenic HIBCH variants in an individual with compatible clinical, biochemical, and imaging findings. If sequencing identifies only one variant, deletion/duplication-sensitive or broader genomic testing may be required.
molecular genetic testing NCIT:C19770 NCI Thesaurus (NCIT)
Results: Biallelic pathogenic or likely pathogenic HIBCH variants establish the diagnosis.
Show evidence (2 references)
PMID:41264763 SUPPORT Other
"The diagnosis of HIBCH deficiency is established in a proband with characteristic clinical, laboratory, and brain imaging findings and biallelic pathogenic variants in HIBCH identified by molecular genetic testing."
GeneReviews identifies molecular detection of biallelic pathogenic variants as confirmatory.
PMID:33762937 SUPPORT Human Clinical
"the targeted NGS testing is costly, and it can not identify possible pathogenic variants in deep intron regions and larger deletions/duplications."
The cohort report identifies relevant limitations of targeted sequencing.
Supportive biochemical testing
Plasma or dried-blood-spot acylcarnitines and urine organic-acid or specialized thiol-conjugate testing can provide biochemical clues. Normal C4-OH or routine metabolites do not exclude the disease, and nonchromatographic C4-OH is not specific.
diagnostic procedure NCIT:C18020 NCI Thesaurus (NCIT)
Results: Specific 3-hydroxyisobutyrylcarnitine, SCPC/SCPCM species, or 2,3-dihydroxy-2-methylbutyrate can support suspicion but require molecular confirmation.
Show evidence (2 references)
PMID:26163321 SUPPORT Human Clinical
"However, we observed normal hydroxy-C4 carnitine levels in one out of two dried blood spots collected after the neonatal period."
Normal C4-OH can occur after the neonatal period.
PMID:26163321 SUPPORT Human Clinical
"Increased hydroxy-C4 carnitine is therefore not specific for HIBCHD"
The metabolite study directly states the C4-OH specificity limitation.
HIBCH enzyme assay in cultured fibroblasts
Specialized measurement of HIBCH activity in cultured skin fibroblasts can provide functional confirmation when molecular or biochemical findings are uncertain.
diagnostic procedure NCIT:C18020 NCI Thesaurus (NCIT)
Results: Markedly decreased or absent HIBCH activity supports the diagnosis.
Show evidence (1 reference)
PMID:24299452 SUPPORT In Vitro
"Fibroblast HIBCH activity was below detectable limits in both patients"
Direct fibroblast testing established the functional enzyme defect in affected siblings.
Brain MRI
Brain MRI characterizes the Leigh-like pattern, especially bilateral pallidal or broader basal-ganglia lesions, but the imaging pattern is supportive rather than specific or confirmatory.
magnetic resonance imaging procedure NCIT:C16809 NCI Thesaurus (NCIT)
Results: Bilateral basal-ganglia lesions support a Leigh-spectrum presentation and direct etiologic testing.
Show evidence (1 reference)
DOI:10.1038/s41439-023-00251-y SUPPORT Human Clinical
"Brain magnetic resonance imaging (MRI) shows bilateral lesions in the basal ganglia with/without brainstem involvement."
The report summarizes the characteristic but nonspecific imaging pattern.
🩻

Imaging Findings

8
Bilateral basal-ganglia lesions on MRI VERY_FREQUENT
Bilateral pallidal, putaminal, or broader basal-ganglia signal abnormalities are the most consistent MRI feature. They occurred in 36 of 38 pooled, largely Leigh-spectrum cases (95%) but are not specific to HIBCH deficiency.
Mri Bilateral Multifocal
Bilateral basal-ganglia lesions basal ganglion UBERON:0002420 Uberon multi-species anatomy ontology (UBERON) Abnormal basal ganglia morphology HP:0002134 Human Phenotype Ontology (HP)
Show evidence (2 references)
PMID:33762937 SUPPORT Human Clinical
"Basal ganglia 8 (100%) 28 (93%) 36 (95%)"
The pooled case table places basal-ganglia involvement in the VERY_FREQUENT band.
DOI:10.1002/jimd.12288 SUPPORT Human Clinical
"Basal ganglia lesions (18 patients) were associated with small cysts in the putamen/pallidum in half of the cases, a characteristic hallmark for diagnosis."
A combined ECHS1/HIBCH series describes putaminal and pallidal lesions, while not establishing HIBCH specificity.
Brainstem abnormalities on MRI FREQUENT
Brainstem involvement was reported in 21 of 38 pooled cases (55%).
Mri
Brainstem abnormalities brainstem UBERON:0002298 Uberon multi-species anatomy ontology (UBERON) Abnormal brainstem morphology HP:0002363 Human Phenotype Ontology (HP)
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Brainstem 6 (75%) 15 (50%) 21 (55%)"
The pooled case table places brainstem involvement in the FREQUENT band.
Cerebral white-matter abnormalities on MRI FREQUENT
White-matter involvement was reported in 13 of 38 pooled cases (34%).
Mri
Cerebral white-matter abnormalities cerebral hemisphere white matter UBERON:0002437 Uberon multi-species anatomy ontology (UBERON) Abnormal cerebral white matter morphology HP:0002500 Human Phenotype Ontology (HP)
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"White matter 3 (38%) 10 (33%) 13 (34%)"
The pooled case table places white-matter involvement in the FREQUENT band.
Cerebral atrophy on MRI FREQUENT
Brain atrophy was reported in 21 of 38 pooled cases (55%).
Mri Diffuse
Cerebral atrophy brain UBERON:0000955 Uberon multi-species anatomy ontology (UBERON) Cerebral atrophy HP:0002059 Human Phenotype Ontology (HP)
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Brain atrophy 3 (38%) 18 (60%) 21 (55%)"
The pooled case table places brain atrophy in the FREQUENT band.
Cerebellar involvement on MRI OCCASIONAL
Cerebellar involvement of unspecified type was reported in 10 of 38 pooled cases (26%); this percentage should not be equated specifically with cerebellar atrophy.
Mri
Cerebellar abnormality cerebellum UBERON:0002037 Uberon multi-species anatomy ontology (UBERON)
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Cerebellum 3 (38%) 7 (23%) 10 (26%)"
The pooled case table places nonspecific cerebellar involvement in the OCCASIONAL band.
Progressive cerebellar atrophy on longitudinal MRI
Progressive cerebellar atrophy is an expanded longitudinal imaging feature documented in individual cases, not a defining finding with an established frequency.
Mri Diffuse
Progressive cerebellar atrophy cerebellum UBERON:0002037 Uberon multi-species anatomy ontology (UBERON) Cerebellar atrophy HP:0001272 Human Phenotype Ontology (HP)
Show evidence (1 reference)
DOI:10.1038/s41439-023-00251-y SUPPORT Human Clinical
"Long-term follow-up MRI revealed progressive cerebellar atrophy, which expands the phenotypic spectrum of HIBCH deficiency."
Longitudinal MRI in one affected patient documents progressive cerebellar atrophy.
Corpus-callosum abnormalities on MRI OCCASIONAL
Corpus-callosum involvement was reported in 6 of 38 pooled cases (16%).
Mri
Corpus-callosum abnormality corpus callosum UBERON:0002336 Uberon multi-species anatomy ontology (UBERON) Abnormal corpus callosum morphology HP:0001273 Human Phenotype Ontology (HP)
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Corpus callosum 1 (13%) 5 (17%) 6 (16%)"
The pooled case table places corpus-callosum involvement in the OCCASIONAL band.
Lactate peak on MR spectroscopy OCCASIONAL
A lactate peak on MR spectroscopy was reported in 4 of 38 pooled cases (11%).
Other
Lactate peak on magnetic resonance spectroscopy
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"MRS lactate peak 1 (13%) 3 (10%) 4 (11%)"
The pooled case table places an MRS lactate peak in the OCCASIONAL band.
📈

Progression

5
Neonatal presentation
Neonatal onset Age: Birth to 29 days
Neonatal-onset disease is the least frequent presentation and carries a high risk of childhood death; survivors may have severe developmental, growth, seizure, and movement-disorder morbidity.
Show evidence (1 reference)
PMID:41264763 SUPPORT Other
"Neonatal onset, the least frequent phenotype, is characterized by hypotonia, seizures, and feeding difficulties at birth. There is a high risk of death in childhood, and individuals that survive typically have developmental delay, seizures, poor weight gain, and growth deficiency and develop a..."
GeneReviews defines the neonatal presentation and its severe course.
Infantile presentation
Infantile onset Age: 1 month to 2 years
Infantile onset is the most common presentation and commonly combines developmental regression, hypotonia, feeding or vomiting symptoms, seizures, movement disorder, and episodic neurologic deterioration.
Show evidence (1 reference)
PMID:41264763 SUPPORT Other
"Infantile onset is the most common phenotype, presenting in the first two years of life with feeding difficulties, vomiting, developmental delay with regression, hypotonia, seizures, movement disorder, microcephaly, vision impairment, and episodes of neurologic deterioration."
GeneReviews defines the infantile presentation and its principal manifestations.
Later-onset progressive movement disorder
Late onset Age: Childhood
Later-onset disease is usually more slowly progressive and has greater reported survival, although the number of observed patients remains small.
Show evidence (1 reference)
PMID:41264763 SUPPORT Other
"Late onset is the second most common phenotype, presenting in childhood as a slowly progressive disease with significant movement disorder with or without paroxysmal dystonia, variable cognitive impairment, and high survivability."
GeneReviews describes the later-onset movement-disorder phenotype.
Illness-associated metabolic-neurologic decompensation
Intercurrent illness or another catabolic stress can precipitate acute encephalopathy or neurologic deterioration. In a pooled, literature-derived series of 40 largely Leigh-spectrum cases, a precipitating cause was reported in 18 (45%).
Show evidence (2 references)
PMID:33762937 SUPPORT Human Clinical
"Precipitating cause 6 (75%) 12 (38%) 18 (45%)"
The pooled case table quantifies reported precipitating events.
DOI:10.1159/000508728 SUPPORT Human Clinical
"recurrent metabolic attacks with intercurrent illness"
The clinical review identifies intercurrent illness as a trigger for recurrent attacks.
Variable survival and long-term disability
Outcome ranges from survival into adulthood to early death. A pooled, literature-ascertained series reported 7 deaths among 40 cases (18%), while a geographically restricted eight-person Bahrain cohort sharing one homozygous variant reported severe disability and sepsis-related mortality.
Show evidence (2 references)
PMID:33762937 SUPPORT Human Clinical
"Death cases 0 7 (22%) 7 (18%)"
The pooled table reports death in 7 of 40 literature-derived cases.
"Despite clinical interventions, 5 of 8 patients exhibited severe, persistent developmental delay, and 3 patients succumbed to sepsis."
This establishes severe outcome in one small, genetically homogeneous regional cohort.
📊

Prevalence

1
Global
Unknown
Population prevalence is not established. The literature consistently describes HIBCH deficiency as rare or very rare, but case-report counts should not be converted into a population prevalence estimate.
Show evidence (2 references)
"Background: 3-Hydroxyisobutyryl-CoA hydrolase (HIBCH) deficiency is a rare inborn error of valine catabolism associated with progressive neurological impairment."
A recent cohort describes the disorder as rare without supplying population prevalence.
DOI:10.1159/000508728 SUPPORT Human Clinical
"HIBCH gene defect is a very rare organic aciduria and also might cause secondary mitochondrial dysfunction."
The literature review describes HIBCH deficiency as very rare.
🔀

Differential Diagnoses

4

Conditions with similar clinical presentations that must be differentiated from 3-hydroxyisobutyryl-CoA hydrolase deficiency:

Overlapping Features ECHS1 acts immediately upstream of HIBCH and can be clinically and biochemically very similar. Chromatographic detection of increased 3-hydroxyisobutyrylcarnitine favors HIBCH deficiency, whereas many other urine intermediates overlap.
Distinguishing Features
  • Increased specific 3-hydroxyisobutyrylcarnitine supports HIBCH deficiency over ECHS1 deficiency.
  • SCPC, SCPCM, and 2,3-dihydroxy-2-methylbutyrate can occur in both disorders.
Show evidence (1 reference)
PMID:26163321 SUPPORT Human Clinical
"With the exception of 3-hydroxyisobutyryl carnitine, the metabolite abnormalities were essentially the same as those observed in patients with ECHS1 mutations"
The metabolite study supplies a direct biochemical discriminator.
Overlapping Features HIBCH deficiency can present with secondary PDH-complex deficiency and a Leigh-like phenotype. Molecular and HIBCH-specific biochemical testing distinguish the secondary finding from a primary PDH disorder.
Show evidence (1 reference)
PMID:24299452 SUPPORT Human Clinical
"HIBCH deficiency, a disorder of valine catabolism, is a novel cause of the multiple mitochondrial dysfunctions syndrome, and should be considered in the differential diagnosis of patients presenting with multiple RC deficiencies and/or pyruvate dehydrogenase deficiency."
The sibling study explicitly identifies the PDH/respiratory-chain diagnostic context.
Overlapping Features Leigh syndrome is a presentation umbrella that HIBCH deficiency can cause, rather than a mutually exclusive diagnosis. Other mitochondrial and nuclear etiologies must be distinguished through molecular testing and disease-specific biochemical clues.
Show evidence (1 reference)
PMID:33762937 SUPPORT Human Clinical
"Applying next-generation sequencing, we identified eight patients with HIBCH mutations from our cohort of 181 cases of genetically diagnosed Leigh/Leigh-like syndrome."
HIBCH deficiency was identified as one molecular cause within a Leigh/Leigh-like cohort.
Propionic and methylmalonic acidemias
Overlapping Features Propionate-pathway disorders can share 2,3-dihydroxy-2-methylbutyrate and acryloyl-CoA-related metabolites. SCPC/SCPCM patterns, acylcarnitines, organic acids, and molecular testing distinguish these disorders.
Show evidence (2 references)
PMID:26163321 SUPPORT Human Clinical
"The metabolites derived from acryloyl-CoA were also increased in patients with inborn errors of propionyl-CoA metabolism"
The metabolite study documents overlap with propionyl-CoA disorders.
PMID:37309295 SUPPORT Other
"Toxicity of accumulating substrates is a significant problem in several disorders of valine and isoleucine degradation notably short-chain enoyl-CoA hydratase (ECHS1 or crotonase) deficiency, 3-hydroxyisobutyryl-CoA hydrolase (HIBCH) deficiency, propionic acidemia (PA), and methylmalonic aciduria (MMA)."
The review places HIBCH, ECHS1, propionic acidemia, and methylmalonic aciduria in an overlapping metabolic context.
{ }

Source YAML

click to show
name: 3-hydroxyisobutyryl-CoA hydrolase deficiency
creation_date: "2026-04-15T00:00:00Z"
category: Mendelian
description: >-
  3-hydroxyisobutyryl-CoA hydrolase (HIBCH) deficiency is an autosomal
  recessive disorder of mitochondrial valine catabolism caused by biallelic
  pathogenic HIBCH variants. The clinical spectrum ranges from severe neonatal
  or infantile neurodegeneration with metabolic decompensation and Leigh-like
  basal-ganglia injury to later-onset progressive movement disorder.
disease_term:
  preferred_term: 3-hydroxyisobutyryl-CoA hydrolase deficiency
  term:
    id: MONDO:0009603
    label: 3-hydroxyisobutyryl-CoA hydrolase deficiency
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0009603
      label: 3-hydroxyisobutyryl-CoA hydrolase deficiency
    mapping_predicate: skos:exactMatch
    mapping_source: MONDO
parents:
- hereditary disease
- inborn error of metabolism
inheritance:
- name: Autosomal Recessive
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  evidence:
  - reference: DOI:10.1159/000508728
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency in a Turkish Child with a Novel HIBCH Gene Mutation and Literature Review
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      3-hydroxyisobutyryl-CoA hydrolase (HIBCH) deficiency (OMIM 250620) is an
      autosomal recessive inborn error of valine catabolism
    explanation: The clinical review explicitly identifies autosomal recessive inheritance.
  - reference: CGGV:assertion_26621ace-7c6b-4a1c-8286-02c4cb8a1544-2019-11-07T222437.403Z
    reference_title: "HIBCH / 3-hydroxyisobutyryl-CoA hydrolase deficiency (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HIBCH | HGNC:4908 | 3-hydroxyisobutyryl-CoA hydrolase deficiency | MONDO:0009603 | AR | Definitive"
    explanation: ClinGen records autosomal recessive inheritance for the definitive gene-disease relationship.
prevalence:
- population: Global
  prevalence_class: UNKNOWN
  notes: >-
    Population prevalence is not established. The literature consistently
    describes HIBCH deficiency as rare or very rare, but case-report counts
    should not be converted into a population prevalence estimate.
  evidence:
  - reference: DOI:10.24911/jbcgenetics.183-1722167696
    reference_title: "Characterization of 3-Hydroxyisobutyryl-Coa Hydrolase (HIBCH) Deficiency in Bahrain: A Retrospective Cohort Study"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Background: 3-Hydroxyisobutyryl-CoA hydrolase (HIBCH) deficiency is a rare inborn error of valine catabolism associated with progressive neurological impairment."
    explanation: A recent cohort describes the disorder as rare without supplying population prevalence.
  - reference: DOI:10.1159/000508728
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency in a Turkish Child with a Novel HIBCH Gene Mutation and Literature Review
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "HIBCH gene defect is a very rare organic aciduria and also might cause secondary mitochondrial dysfunction."
    explanation: The literature review describes HIBCH deficiency as very rare.
has_subtypes:
- name: Neonatal onset
  description: >-
    The least frequent and generally most severe presentation, beginning at
    birth with feeding difficulty, tone abnormality, and seizures.
- name: Infantile onset
  description: >-
    The most common presentation, beginning in the first two years with
    neurodevelopmental delay or regression, hypotonia, movement disorder, and
    episodic neurologic deterioration.
- name: Late onset
  description: >-
    A childhood-onset, more slowly progressive presentation dominated by
    movement disorder, sometimes paroxysmal dystonia, and variable cognitive
    impairment.
progression:
- phase: Neonatal presentation
  subtype: Neonatal onset
  age_range: Birth to 29 days
  notes: >-
    Neonatal-onset disease is the least frequent presentation and carries a
    high risk of childhood death; survivors may have severe developmental,
    growth, seizure, and movement-disorder morbidity.
  evidence:
  - reference: PMID:41264763
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Neonatal onset, the least frequent phenotype, is characterized by
      hypotonia, seizures, and feeding difficulties at birth. There is a high
      risk of death in childhood, and individuals that survive typically have
      developmental delay, seizures, poor weight gain, and growth deficiency
      and develop a movement disorder.
    explanation: GeneReviews defines the neonatal presentation and its severe course.
- phase: Infantile presentation
  subtype: Infantile onset
  age_range: 1 month to 2 years
  notes: >-
    Infantile onset is the most common presentation and commonly combines
    developmental regression, hypotonia, feeding or vomiting symptoms,
    seizures, movement disorder, and episodic neurologic deterioration.
  evidence:
  - reference: PMID:41264763
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Infantile onset is the most common phenotype, presenting in the first two
      years of life with feeding difficulties, vomiting, developmental delay
      with regression, hypotonia, seizures, movement disorder, microcephaly,
      vision impairment, and episodes of neurologic deterioration.
    explanation: GeneReviews defines the infantile presentation and its principal manifestations.
- phase: Later-onset progressive movement disorder
  subtype: Late onset
  age_range: Childhood
  notes: >-
    Later-onset disease is usually more slowly progressive and has greater
    reported survival, although the number of observed patients remains small.
  evidence:
  - reference: PMID:41264763
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Late onset is the second most common phenotype, presenting in childhood
      as a slowly progressive disease with significant movement disorder with
      or without paroxysmal dystonia, variable cognitive impairment, and high
      survivability.
    explanation: GeneReviews describes the later-onset movement-disorder phenotype.
- phase: Illness-associated metabolic-neurologic decompensation
  notes: >-
    Intercurrent illness or another catabolic stress can precipitate acute
    encephalopathy or neurologic deterioration. In a pooled, literature-derived
    series of 40 largely Leigh-spectrum cases, a precipitating cause was
    reported in 18 (45%).
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Precipitating cause 6 (75%) 12 (38%) 18 (45%)"
    explanation: The pooled case table quantifies reported precipitating events.
  - reference: DOI:10.1159/000508728
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency in a Turkish Child with a Novel HIBCH Gene Mutation and Literature Review
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "recurrent metabolic attacks with intercurrent illness"
    explanation: The clinical review identifies intercurrent illness as a trigger for recurrent attacks.
- phase: Variable survival and long-term disability
  notes: >-
    Outcome ranges from survival into adulthood to early death. A pooled,
    literature-ascertained series reported 7 deaths among 40 cases (18%), while
    a geographically restricted eight-person Bahrain cohort sharing one
    homozygous variant reported severe disability and sepsis-related mortality.
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Death cases 0 7 (22%) 7 (18%)"
    explanation: The pooled table reports death in 7 of 40 literature-derived cases.
  - reference: DOI:10.24911/jbcgenetics.183-1722167696
    reference_title: "Characterization of 3-Hydroxyisobutyryl-Coa Hydrolase (HIBCH) Deficiency in Bahrain: A Retrospective Cohort Study"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Despite clinical interventions, 5 of 8 patients exhibited severe, persistent developmental delay, and 3 patients succumbed to sepsis."
    explanation: This establishes severe outcome in one small, genetically homogeneous regional cohort.
mechanistic_hypotheses:
- hypothesis_group_id: canonical_hibch_reactive_metabolite_model
  hypothesis_label: Canonical HIBCH Reactive-Metabolite Model
  status: CANONICAL
  description: >-
    Loss of HIBCH activity blocks hydrolysis of 3-hydroxyisobutyryl-CoA.
    Accumulated valine-pathway intermediates are associated with
    3-hydroxyisobutyrylcarnitine and methacrylyl-CoA-derived thiol conjugates.
    Reactive intermediate toxicity is proposed to impair mitochondrial proteins
    and energy metabolism, but the causal steps and the reason for selective
    basal-ganglia vulnerability are not fully established in humans.
  evidence:
  - reference: PMID:26163321
    reference_title: "Metabolite studies in HIBCH and ECHS1 defects: Implications for screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Urine metabolite investigations also showed increases in
      3-hydroxyisobutyryl carnitine, 2,3-dihydroxy-2-methylbutyrate and several
      metabolites indicating accumulation and subsequent metabolism of
      methacrylyl-CoA and acryloyl-CoA.
    explanation: Human metabolite studies support accumulation of valine-derived intermediates.
  - reference: PMID:24299452
    reference_title: HIBCH mutations can cause Leigh-like disease with combined deficiency of multiple mitochondrial respiratory chain enzymes and pyruvate dehydrogenase.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The index case had deficiencies of multiple RC enzymes and PDHc in
      skeletal muscle and fibroblasts respectively, but these were normal in his
      younger brother.
    explanation: Human secondary mitochondrial abnormalities support part of the model but their sibling discordance shows that they are not required.
- hypothesis_group_id: emerging_hibch_lysine_methacrylation_model
  hypothesis_label: Emerging Lysine Methacrylation Model
  status: EMERGING
  description: >-
    Cell, patient-fibroblast, and Drosophila experiments implicate ectopic
    protein lysine methacrylation in mitochondrial morphology and respiratory
    defects. This is an emerging preclinical mechanism and does not establish a
    human therapy.
  evidence:
  - reference: PMID:40056416
    reference_title: Ectopic protein lysine methacrylation contributes to defects caused by loss of HIBCH or ECHS1.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Fibroblasts from patients with HIBCH or ECHS1 mutations show similar
      mitochondrial changes and elevated Kmea, which are significantly reversed
      by administering N-acetyl-L-cysteine to reduce Kmea levels.
    explanation: Patient fibroblasts support an in-vitro methacrylation phenotype and experimental rescue.
  - reference: PMID:40056416
    reference_title: Ectopic protein lysine methacrylation contributes to defects caused by loss of HIBCH or ECHS1.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Reducing Kmea modification partially rescues mitochondrial morphology
      changes in cells and eye degeneration in flies.
    explanation: Rescue in flies is preclinical and cannot be interpreted as clinical efficacy.
pathophysiology:
- name: HIBCH catalytic loss
  description: >-
    Biallelic pathogenic HIBCH variants reduce mitochondrial
    3-hydroxyisobutyryl-CoA hydrolase activity, establishing the initiating
    enzymatic lesion.
  gene:
    preferred_term: HIBCH
    term:
      id: hgnc:4908
      label: HIBCH
  molecular_functions:
  - preferred_term: 3-hydroxyisobutyryl-CoA hydrolase activity
    term:
      id: GO:0003860
      label: 3-hydroxyisobutyryl-CoA hydrolase activity
    modifier: DECREASED
  locations:
  - preferred_term: mitochondrial matrix
    term:
      id: GO:0005759
      label: mitochondrial matrix
  mechanism_confidence: ESTABLISHED
  evidence:
  - reference: PMID:24299452
    reference_title: HIBCH mutations can cause Leigh-like disease with combined deficiency of multiple mitochondrial respiratory chain enzymes and pyruvate dehydrogenase.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Fibroblast HIBCH activity was below detectable limits in both patients"
    explanation: Enzyme assay demonstrated absent detectable activity in fibroblasts from two affected siblings.
  - reference: CGGV:assertion_26621ace-7c6b-4a1c-8286-02c4cb8a1544-2019-11-07T222437.403Z
    reference_title: "HIBCH / 3-hydroxyisobutyryl-CoA hydrolase deficiency (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HIBCH | HGNC:4908 | 3-hydroxyisobutyryl-CoA hydrolase deficiency | MONDO:0009603 | AR | Definitive"
    explanation: ClinGen classifies the HIBCH-disease relationship as definitive.
  downstream:
  - target: Impaired 3-hydroxyisobutyryl-CoA hydrolysis
    description: Loss of the enzyme directly blocks its mitochondrial valine-catabolism reaction.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:26163321
      reference_title: "Metabolite studies in HIBCH and ECHS1 defects: Implications for screening."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "conversion of 3-hydroxyisobutyryl-CoA to free 3-hydroxyisobutyrate"
      explanation: The paper states the reaction directly.
- name: Impaired 3-hydroxyisobutyryl-CoA hydrolysis
  description: >-
    Failure to convert 3-hydroxyisobutyryl-CoA to free
    3-hydroxyisobutyrate disrupts mitochondrial valine catabolism.
  biological_processes:
  - preferred_term: valine catabolic process
    term:
      id: GO:0006574
      label: L-valine catabolic process
    modifier: DECREASED
  chemical_entities:
  - preferred_term: L-valine
    term:
      id: CHEBI:16414
      label: L-valine
  - preferred_term: 3-hydroxyisobutyryl-CoA
  locations:
  - preferred_term: mitochondrial matrix
    term:
      id: GO:0005759
      label: mitochondrial matrix
  mechanism_confidence: ESTABLISHED
  evidence:
  - reference: PMID:26163321
    reference_title: "Metabolite studies in HIBCH and ECHS1 defects: Implications for screening."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "conversion of 3-hydroxyisobutyryl-CoA to free 3-hydroxyisobutyrate"
    explanation: This defines the blocked reaction.
  downstream:
  - target: Reactive valine-derived intermediate accumulation
    description: >-
      Substrate accumulation and pathway back-pressure are associated with
      methacrylyl-CoA- and acryloyl-CoA-derived metabolites.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:26163321
      reference_title: "Metabolite studies in HIBCH and ECHS1 defects: Implications for screening."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Urine metabolite investigations also showed increases in
        3-hydroxyisobutyryl carnitine, 2,3-dihydroxy-2-methylbutyrate and
        several metabolites indicating accumulation and subsequent metabolism
        of methacrylyl-CoA and acryloyl-CoA.
      explanation: Human metabolites support pathway accumulation, while the precise back-pressure mechanism is unresolved.
- name: Reactive valine-derived intermediate accumulation
  description: >-
    Methacrylyl-CoA and related electrophilic intermediates can react with
    sulfhydryl-containing molecules. SCPC, SCPCM, their derivatives, and other
    urine metabolites report this biochemical state; their contribution to
    neural injury remains incompletely defined.
  chemical_entities:
  - preferred_term: methacrylyl-CoA
    term:
      id: CHEBI:27754
      label: methacrylyl-CoA
  locations:
  - preferred_term: mitochondrial matrix
    term:
      id: GO:0005759
      label: mitochondrial matrix
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:26163321
    reference_title: "Metabolite studies in HIBCH and ECHS1 defects: Implications for screening."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Urine tandem mass spectrometry screening showed large increases in the cysteine conjugate of methacrylate previously described in HIBCHD."
    explanation: The biochemical reactivity of methacrylyl-CoA supports the toxicity model.
  downstream:
  - target: Variable secondary PDH and respiratory-chain dysfunction
    description: >-
      Reactive-intermediate and redox effects may impair mitochondrial enzymes,
      but abnormalities are inconsistent among affected people.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:24299452
      reference_title: HIBCH mutations can cause Leigh-like disease with combined deficiency of multiple mitochondrial respiratory chain enzymes and pyruvate dehydrogenase.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        These effects are likely to vary according to the levels of oxidative
        stress, which may explain the variable RC and PDHc defects seen in the
        3 patients with HIBCH deficiency
      explanation: The study explicitly treats the mechanism and variability as explanatory hypotheses.
  - target: Illness-associated acute neurometabolic decompensation
    description: >-
      Catabolic stress may increase valine-pathway flux and reactive-metabolite
      burden, contributing to illness-associated deterioration.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Increased valine release and pathway flux during catabolism or ketosis.
    evidence:
    - reference: DOI:10.1159/000508728
      reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency in a Turkish Child with a Novel HIBCH Gene Mutation and Literature Review
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "recurrent metabolic attacks with intercurrent illness"
      explanation: Human clinical evidence supports illness-associated attacks; increased valine-pathway flux remains the inferred intermediate.
  - target: Leigh-like basal-ganglia neurometabolic injury
    description: >-
      Reactive metabolite toxicity may injure vulnerable neural tissue through
      mechanisms that do not require demonstrable respiratory-chain or PDH
      deficiency in every patient.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:24299452
      reference_title: HIBCH mutations can cause Leigh-like disease with combined deficiency of multiple mitochondrial respiratory chain enzymes and pyruvate dehydrogenase.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The predilection for the basal ganglia in HIBCH deficiency is
        intriguing, and the pathomechanism(s) underlying the basal ganglia
        lesions, and in particular the selective involvement of the globi
        pallidi and subthalamic nuclei, are not clear.
      explanation: Human imaging establishes selective vulnerability while explicitly leaving its mechanism unresolved.
- name: Variable secondary PDH and respiratory-chain dysfunction
  description: >-
    Secondary pyruvate-dehydrogenase-complex and respiratory-chain
    abnormalities occur in some patients, but are neither universal nor a
    required bottleneck for the neurologic phenotype.
  biological_processes:
  - preferred_term: oxidative phosphorylation
    term:
      id: GO:0006119
      label: oxidative phosphorylation
    modifier: DECREASED
  locations:
  - preferred_term: mitochondrion
    term:
      id: GO:0005739
      label: mitochondrion
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:24299452
    reference_title: HIBCH mutations can cause Leigh-like disease with combined deficiency of multiple mitochondrial respiratory chain enzymes and pyruvate dehydrogenase.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The index case had deficiencies of multiple RC enzymes and PDHc in
      skeletal muscle and fibroblasts respectively, but these were normal in his
      younger brother.
    explanation: Two similarly affected siblings demonstrate that the biochemical abnormality is variable.
  - reference: DOI:10.24911/jbcgenetics.183-1722167696
    reference_title: "Characterization of 3-Hydroxyisobutyryl-Coa Hydrolase (HIBCH) Deficiency in Bahrain: A Retrospective Cohort Study"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Biochemical profiling revealed elevated C4-OH acylcarnitine, with variable abnormalities in blood lactate, amino acids, and respiratory chain complexes."
    explanation: The Bahrain cohort independently describes respiratory-chain abnormalities as variable.
  downstream:
  - target: Leigh-like basal-ganglia neurometabolic injury
    description: Energy-metabolism impairment may contribute to Leigh-like injury in the subset with secondary enzyme defects.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:24299452
      reference_title: HIBCH mutations can cause Leigh-like disease with combined deficiency of multiple mitochondrial respiratory chain enzymes and pyruvate dehydrogenase.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        It is possible that the lesions arise from localised cerebral energy
        failure and subsequent neuronal cell death
      explanation: The energy-failure link is explicitly proposed rather than demonstrated.
- name: Illness-associated acute neurometabolic decompensation
  description: >-
    Intercurrent illness, fasting, or another catabolic stress can precipitate
    acute encephalopathy and neurologic deterioration on the background of
    disrupted valine metabolism.
  mechanism_confidence: ESTABLISHED
  evidence:
  - reference: DOI:10.1159/000508728
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency in a Turkish Child with a Novel HIBCH Gene Mutation and Literature Review
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "recurrent metabolic attacks with intercurrent illness"
    explanation: Illness-associated attacks are a documented part of the clinical course.
  - reference: PMID:41264763
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "episodes of neurologic deterioration"
    explanation: GeneReviews includes episodic deterioration in the common infantile presentation.
  downstream:
  - target: Developmental regression
    description: Acute neurologic deterioration can result in loss of acquired skills.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Encephalopathy
    description: Acute decompensation manifests clinically as encephalopathy in many reported cases.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Leigh-like basal-ganglia neurometabolic injury
  description: >-
    HIBCH deficiency commonly produces a Leigh-like syndrome with bilateral
    pallidal or broader basal-ganglia injury. The selective neuroanatomic
    vulnerability is observed consistently, but its molecular basis remains
    unresolved.
  locations:
  - preferred_term: basal ganglion
    term:
      id: UBERON:0002420
      label: basal ganglion
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Basal ganglia 8 (100%) 28 (93%) 36 (95%)"
    explanation: Basal-ganglia involvement occurred in 36 of 38 pooled, largely Leigh-spectrum cases with imaging data.
  - reference: PMID:24299452
    reference_title: HIBCH mutations can cause Leigh-like disease with combined deficiency of multiple mitochondrial respiratory chain enzymes and pyruvate dehydrogenase.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Two brothers born to distantly related Pakistani parents presenting in
      early infancy with a progressive neurodegenerative disorder, associated
      with basal ganglia changes on brain magnetic resonance imaging
    explanation: The sibling report establishes the Leigh-like clinical-imaging presentation.
  downstream:
  - target: Developmental regression
    description: Progressive or episodic neural injury is associated with regression.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Hypotonia
    description: Central neurometabolic injury is associated with hypotonia.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Dystonia
    description: Basal-ganglia circuit injury is associated with dystonia.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
phenotypes:
- name: Global developmental delay
  category: Neurologic
  frequency: FREQUENT
  description: >-
    Developmental delay was reported in 29 of 38 pooled,
    literature-ascertained cases (76%); the cohort was enriched for
    Leigh/Leigh-like presentations.
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Developmental delay 5 (63%) 24 (80%) 29 (76%)"
    explanation: The pooled case table places developmental delay in the FREQUENT band.
- name: Developmental regression
  category: Neurologic
  frequency: FREQUENT
  description: >-
    Loss of acquired skills was reported in 24 of 38 pooled,
    literature-ascertained cases (63%).
  phenotype_term:
    preferred_term: Developmental regression
    term:
      id: HP:0002376
      label: Developmental regression
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Developmental regression 7 (88%) 17 (57%) 24 (63%)"
    explanation: The pooled case table places regression in the FREQUENT band.
- name: Hypotonia
  category: Neurologic
  frequency: FREQUENT
  description: Hypotonia was reported in 28 of 38 pooled cases (74%).
  phenotype_term:
    preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hypotonia 8 (100%) 20 (67%) 28 (74%)"
    explanation: The pooled case table places hypotonia in the FREQUENT band.
- name: Encephalopathy
  category: Neurologic
  frequency: FREQUENT
  description: Encephalopathy was reported in 19 of 38 pooled cases (50%).
  phenotype_term:
    preferred_term: Encephalopathy
    term:
      id: HP:0001298
      label: Encephalopathy
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Encephalopathy 6 (75%) 13 (43%) 19 (50%)"
    explanation: The pooled case table places encephalopathy in the FREQUENT band.
- name: Feeding difficulties
  category: Gastrointestinal
  frequency: FREQUENT
  description: Feeding difficulty was reported in 19 of 38 pooled cases (50%).
  phenotype_term:
    preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Feeding dif ficulties 5 (63%) 14 (47%) 19 (50%)"
    explanation: The pooled case table places feeding difficulty in the FREQUENT band.
- name: Dystonia
  category: Neurologic
  frequency: FREQUENT
  description: Dystonia was reported in 19 of 38 pooled cases (50%).
  phenotype_term:
    preferred_term: Dystonia
    term:
      id: HP:0001332
      label: Dystonia
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Dystonia 4 (50%) 15 (50%) 19 (50%)"
    explanation: The pooled case table places dystonia in the FREQUENT band.
- name: Ataxia
  category: Neurologic
  frequency: FREQUENT
  description: Ataxia was reported in 15 of 38 pooled cases (40%).
  phenotype_term:
    preferred_term: Ataxia
    term:
      id: HP:0001251
      label: Ataxia
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Ataxia 4 (50%) 11 (37%) 15 (40%)"
    explanation: The pooled case table places ataxia in the FREQUENT band.
- name: Seizure
  category: Neurologic
  frequency: FREQUENT
  description: Seizures were reported in 13 of 38 pooled cases (34%).
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Seizures 3 (38%) 10 (33%) 13 (34%)"
    explanation: The pooled case table places seizures in the FREQUENT band.
- name: Nystagmus
  category: Ophthalmologic
  frequency: FREQUENT
  description: Nystagmus was reported in 14 of 38 pooled cases (37%).
  phenotype_term:
    preferred_term: Nystagmus
    term:
      id: HP:0000639
      label: Nystagmus
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Nystagmus 3 (38%) 11 (37%) 14 (37%)"
    explanation: The pooled case table places nystagmus in the FREQUENT band.
- name: Strabismus
  category: Ophthalmologic
  frequency: OCCASIONAL
  description: Strabismus was reported in 10 of 38 pooled cases (26%).
  phenotype_term:
    preferred_term: Strabismus
    term:
      id: HP:0000486
      label: Strabismus
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Strabismus 4 (50%) 6 (20%) 10 (26%)"
    explanation: The pooled case table places strabismus in the OCCASIONAL band.
- name: Optic atrophy
  category: Ophthalmologic
  frequency: OCCASIONAL
  description: Optic atrophy was reported in 5 of 38 pooled cases (13%).
  phenotype_term:
    preferred_term: Optic atrophy
    term:
      id: HP:0000648
      label: Optic atrophy
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Optic atrophy 0 5 (17%) 5 (13%)"
    explanation: The pooled case table places optic atrophy in the OCCASIONAL band.
- name: Vomiting
  category: Gastrointestinal
  subtype: Infantile onset
  description: Vomiting is part of the common infantile-onset presentation.
  phenotype_term:
    preferred_term: Vomiting
    term:
      id: HP:0002013
      label: Vomiting
  evidence:
  - reference: PMID:41264763
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Infantile onset is the most common phenotype, presenting in the first two
      years of life with feeding difficulties, vomiting, developmental delay
      with regression
    explanation: GeneReviews includes vomiting in the infantile phenotype.
- name: Microcephaly
  category: Neurologic
  subtype: Infantile onset
  description: Microcephaly occurs in the infantile-onset spectrum.
  phenotype_term:
    preferred_term: Microcephaly
    term:
      id: HP:0000252
      label: Microcephaly
  evidence:
  - reference: PMID:41264763
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      movement disorder, microcephaly, vision impairment, and episodes of
      neurologic deterioration
    explanation: GeneReviews includes microcephaly in the infantile phenotype.
- name: Spasticity
  category: Neurologic
  description: Spasticity can emerge during the progressive neurologic course.
  phenotype_term:
    preferred_term: Spasticity
    term:
      id: HP:0001257
      label: Spasticity
  evidence:
  - reference: DOI:10.1038/s41439-023-00251-y
    reference_title: Leigh-like syndrome with progressive cerebellar atrophy caused by novel HIBCH variants
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the patient subsequently developed various new symptoms, including
      nystagmus, athetosis, and spastic paraparesis.
    explanation: Longitudinal follow-up documents emergence of spastic paraparesis in an affected patient.
- name: Failure to thrive
  category: Growth
  subtype: Neonatal onset
  description: Poor weight gain and growth deficiency can complicate severe early-onset disease.
  phenotype_term:
    preferred_term: Failure to thrive
    term:
      id: HP:0001508
      label: Failure to thrive
  evidence:
  - reference: PMID:41264763
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      individuals that survive typically have developmental delay, seizures,
      poor weight gain, and growth deficiency
    explanation: GeneReviews describes poor weight gain and growth deficiency among neonatal-onset survivors.
- name: Cognitive impairment
  category: Neurologic
  subtype: Late onset
  description: Cognitive impairment is variable in later-onset disease.
  phenotype_term:
    preferred_term: Cognitive impairment
    term:
      id: HP:0100543
      label: Cognitive impairment
  evidence:
  - reference: PMID:41264763
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      significant movement disorder with or without paroxysmal dystonia,
      variable cognitive impairment, and high survivability.
    explanation: GeneReviews includes variable cognitive impairment in later-onset disease.
imaging_findings:
- name: Bilateral basal-ganglia lesions on MRI
  modality: MRI
  imaging_finding_term:
    preferred_term: Bilateral basal-ganglia lesions
  phenotype_term:
    preferred_term: Abnormal basal ganglia morphology
    term:
      id: HP:0002134
      label: Abnormal basal ganglia morphology
  located_in:
    preferred_term: basal ganglion
    term:
      id: UBERON:0002420
      label: basal ganglion
  laterality: BILATERAL
  spatial_extent: MULTIFOCAL
  frequency: VERY_FREQUENT
  description: >-
    Bilateral pallidal, putaminal, or broader basal-ganglia signal abnormalities
    are the most consistent MRI feature. They occurred in 36 of 38 pooled,
    largely Leigh-spectrum cases (95%) but are not specific to HIBCH deficiency.
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Basal ganglia 8 (100%) 28 (93%) 36 (95%)"
    explanation: The pooled case table places basal-ganglia involvement in the VERY_FREQUENT band.
  - reference: DOI:10.1002/jimd.12288
    reference_title: "Delineating the neurological phenotype in children with defects in the <scp><i>ECHS1</i></scp> or <scp><i>HIBCH</i></scp> gene"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Basal ganglia lesions (18 patients) were associated with small cysts in the putamen/pallidum in half of the cases, a characteristic hallmark for diagnosis."
    explanation: A combined ECHS1/HIBCH series describes putaminal and pallidal lesions, while not establishing HIBCH specificity.
- name: Brainstem abnormalities on MRI
  modality: MRI
  imaging_finding_term:
    preferred_term: Brainstem abnormalities
  phenotype_term:
    preferred_term: Abnormal brainstem morphology
    term:
      id: HP:0002363
      label: Abnormal brainstem morphology
  located_in:
    preferred_term: brainstem
    term:
      id: UBERON:0002298
      label: brainstem
  frequency: FREQUENT
  description: Brainstem involvement was reported in 21 of 38 pooled cases (55%).
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Brainstem 6 (75%) 15 (50%) 21 (55%)"
    explanation: The pooled case table places brainstem involvement in the FREQUENT band.
- name: Cerebral white-matter abnormalities on MRI
  modality: MRI
  imaging_finding_term:
    preferred_term: Cerebral white-matter abnormalities
  phenotype_term:
    preferred_term: Abnormal cerebral white matter morphology
    term:
      id: HP:0002500
      label: Abnormal cerebral white matter morphology
  located_in:
    preferred_term: cerebral hemisphere white matter
    term:
      id: UBERON:0002437
      label: cerebral hemisphere white matter
  frequency: FREQUENT
  description: White-matter involvement was reported in 13 of 38 pooled cases (34%).
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "White matter 3 (38%) 10 (33%) 13 (34%)"
    explanation: The pooled case table places white-matter involvement in the FREQUENT band.
- name: Cerebral atrophy on MRI
  modality: MRI
  imaging_finding_term:
    preferred_term: Cerebral atrophy
  phenotype_term:
    preferred_term: Cerebral atrophy
    term:
      id: HP:0002059
      label: Cerebral atrophy
  located_in:
    preferred_term: brain
    term:
      id: UBERON:0000955
      label: brain
  spatial_extent: DIFFUSE
  frequency: FREQUENT
  description: Brain atrophy was reported in 21 of 38 pooled cases (55%).
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Brain atrophy 3 (38%) 18 (60%) 21 (55%)"
    explanation: The pooled case table places brain atrophy in the FREQUENT band.
- name: Cerebellar involvement on MRI
  modality: MRI
  imaging_finding_term:
    preferred_term: Cerebellar abnormality
  located_in:
    preferred_term: cerebellum
    term:
      id: UBERON:0002037
      label: cerebellum
  frequency: OCCASIONAL
  description: >-
    Cerebellar involvement of unspecified type was reported in 10 of 38 pooled
    cases (26%); this percentage should not be equated specifically with
    cerebellar atrophy.
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Cerebellum 3 (38%) 7 (23%) 10 (26%)"
    explanation: The pooled case table places nonspecific cerebellar involvement in the OCCASIONAL band.
- name: Progressive cerebellar atrophy on longitudinal MRI
  modality: MRI
  imaging_finding_term:
    preferred_term: Progressive cerebellar atrophy
  phenotype_term:
    preferred_term: Cerebellar atrophy
    term:
      id: HP:0001272
      label: Cerebellar atrophy
  located_in:
    preferred_term: cerebellum
    term:
      id: UBERON:0002037
      label: cerebellum
  spatial_extent: DIFFUSE
  description: >-
    Progressive cerebellar atrophy is an expanded longitudinal imaging feature
    documented in individual cases, not a defining finding with an established
    frequency.
  evidence:
  - reference: DOI:10.1038/s41439-023-00251-y
    reference_title: Leigh-like syndrome with progressive cerebellar atrophy caused by novel HIBCH variants
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Long-term follow-up MRI revealed progressive cerebellar atrophy, which expands the phenotypic spectrum of HIBCH deficiency."
    explanation: Longitudinal MRI in one affected patient documents progressive cerebellar atrophy.
- name: Corpus-callosum abnormalities on MRI
  modality: MRI
  imaging_finding_term:
    preferred_term: Corpus-callosum abnormality
  phenotype_term:
    preferred_term: Abnormal corpus callosum morphology
    term:
      id: HP:0001273
      label: Abnormal corpus callosum morphology
  located_in:
    preferred_term: corpus callosum
    term:
      id: UBERON:0002336
      label: corpus callosum
  frequency: OCCASIONAL
  description: Corpus-callosum involvement was reported in 6 of 38 pooled cases (16%).
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Corpus callosum 1 (13%) 5 (17%) 6 (16%)"
    explanation: The pooled case table places corpus-callosum involvement in the OCCASIONAL band.
- name: Lactate peak on MR spectroscopy
  modality: OTHER
  imaging_finding_term:
    preferred_term: Lactate peak on magnetic resonance spectroscopy
  frequency: OCCASIONAL
  description: A lactate peak on MR spectroscopy was reported in 4 of 38 pooled cases (11%).
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "MRS lactate peak 1 (13%) 3 (10%) 4 (11%)"
    explanation: The pooled case table places an MRS lactate peak in the OCCASIONAL band.
biochemical:
- name: 3-hydroxyisobutyrylcarnitine (C4-OH)
  presence: INCREASED
  frequency: FREQUENT
  specificity: >-
    Limited without chromatographic isomer separation; routine C4-OH can include
    3-hydroxybutyrylcarnitine and may be normal in HIBCH deficiency.
  context: >-
    Elevated blood C4-OH was reported in 20 of 31 tested pooled cases (65%).
    Specific measurement of 3-hydroxyisobutyrylcarnitine is more informative
    than a nonchromatographic aggregate C4-OH signal.
  readouts:
  - target: Impaired 3-hydroxyisobutyryl-CoA hydrolysis
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Substrate-derived 3-hydroxyisobutyrylcarnitine reports the HIBCH hydrolysis block.
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Elevated blood C4-OH 5/8 (63%) 15/23 (65%) 20/31 (65%)"
    explanation: The pooled table places elevated C4-OH in the FREQUENT band but shows it is not universal.
  - reference: PMID:26163321
    reference_title: "Metabolite studies in HIBCH and ECHS1 defects: Implications for screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Increased hydroxy-C4 carnitine is therefore not specific for HIBCHD"
    explanation: The study directly identifies isomeric interference and limited specificity.
- name: Urinary 2,3-dihydroxy-2-methylbutyrate
  presence: INCREASED
  frequency: FREQUENT
  specificity: >-
    Limited; it also occurs in ECHS1 deficiency and propionate disorders, and
    its exact route of formation remains uncertain.
  context: Elevated in 8 of 15 tested pooled cases (53%).
  readouts:
  - target: Reactive valine-derived intermediate accumulation
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: This urine metabolite is associated with reactive valine/propionate-pathway intermediates but is not HIBCH-specific.
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Elevated urine 23HD2MB 6/7 (86%) 2/8 (25%) 8/15 (53%)"
    explanation: The pooled table places this metabolite in the FREQUENT band with a small denominator.
  - reference: PMID:26163321
    reference_title: "Metabolite studies in HIBCH and ECHS1 defects: Implications for screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Patients with propionic acidaemia were investigated and found to have
      increased urine levels of 23DH2MB
    explanation: Its occurrence in propionic acidemia limits specificity.
- name: Urinary S-(2-carboxypropyl)cysteine and its carnitine ester
  presence: INCREASED
  specificity: >-
    More directly reflects methacrylyl-CoA thiol conjugation, but also occurs in
    ECHS1 deficiency and requires specialized analysis.
  context: >-
    SCPC and its carnitine ester are specialized urine markers not captured by
    routine organic-acid or acylcarnitine testing.
  readouts:
  - target: Reactive valine-derived intermediate accumulation
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: SCPC species report conjugation of reactive methacrylyl-derived intermediates.
  evidence:
  - reference: PMID:26163321
    reference_title: "Metabolite studies in HIBCH and ECHS1 defects: Implications for screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Semi-quantitative urine screening by tandem mass spectrometry revealed
      increased excretion of SCPC in samples from the HIBCHD and SCEHD patients
      (Fig. 2A).
    explanation: Specialized urine tandem mass spectrometry detected SCPC in HIBCH and ECHS1 deficiency.
  - reference: PMID:26163321
    reference_title: "Metabolite studies in HIBCH and ECHS1 defects: Implications for screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the carnitine ester of SCPC were also found in the HIBCHD and SCEHD patients."
    explanation: The same study identifies the SCPC carnitine ester as a related marker.
- name: Urinary S-(2-carboxypropyl)cysteamine
  presence: INCREASED
  specificity: Potentially useful, but sensitivity and specificity are not established.
  context: >-
    SCPCM was elevated in all five selected published cases in which it was
    measured; this tiny, selected denominator must not be interpreted as 100%
    clinical sensitivity.
  readouts:
  - target: Reactive valine-derived intermediate accumulation
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: SCPCM is a methacrylyl-CoA-derived thiol conjugate.
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Elevated urine SCPCM 3/3 (100%) 2/2 (100%) 5/5 (100%)"
    explanation: The pooled table reports five positive selected tests, not population-level sensitivity.
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SCPCM seems to be more speci fic for disease diagnosis, but more samples are needed for verification."
    explanation: The authors explicitly qualify the marker as requiring further validation.
- name: Blood lactate
  presence: Variable
  frequency: FREQUENT
  specificity: Low
  context: >-
    Blood lactate was elevated in 15 of 35 tested pooled cases (43%); normal
    lactate therefore does not exclude HIBCH deficiency.
  readouts:
  - target: Variable secondary PDH and respiratory-chain dysfunction
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Elevated lactate is a nonspecific, inconsistent marker of secondary energy-metabolism dysfunction.
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Increased blood lactate level 3/8 (38%) 12/27 (44%) 15/35 (43%)"
    explanation: The pooled table places elevated lactate in the FREQUENT band while demonstrating variability.
- name: HIBCH activity in cultured skin fibroblasts
  presence: DECREASED
  frequency: VERY_FREQUENT
  specificity: High when measured with an appropriate enzyme assay.
  context: >-
    Activity was decreased in all 11 selected published cases with reported
    fibroblast testing; this is an assay result in a small, clinically selected
    denominator.
  readouts:
  - target: HIBCH catalytic loss
    relationship: READOUT_OF
    direction: NEGATIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Reduced enzyme activity directly measures the initiating catalytic defect.
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Decreased HIBCH activity in skin fibroblasts — 11/11 (100%) 11/11 (100%)"
    explanation: The pooled table reports decreased activity in all 11 tested published cases.
  - reference: PMID:24299452
    reference_title: HIBCH mutations can cause Leigh-like disease with combined deficiency of multiple mitochondrial respiratory chain enzymes and pyruvate dehydrogenase.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Fibroblast HIBCH activity was below detectable limits in both patients"
    explanation: Direct enzyme testing confirmed absent detectable activity in affected siblings.
genetic:
- name: HIBCH pathogenic variants
  association: Biallelic loss of function
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  gene_term:
    preferred_term: HIBCH
    term:
      id: hgnc:4908
      label: HIBCH
  inheritance:
  - name: Autosomal Recessive
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  features: >-
    The diagnosis requires biallelic pathogenic or likely pathogenic HIBCH
    variants; variants of uncertain significance do not establish the
    diagnosis without additional evidence.
  evidence:
  - reference: PMID:41264763
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The diagnosis of HIBCH deficiency is established in a proband with
      characteristic clinical, laboratory, and brain imaging findings and
      biallelic pathogenic variants in HIBCH identified by molecular genetic
      testing.
    explanation: GeneReviews defines the biallelic molecular diagnostic requirement.
  - reference: CGGV:assertion_26621ace-7c6b-4a1c-8286-02c4cb8a1544-2019-11-07T222437.403Z
    reference_title: "HIBCH / 3-hydroxyisobutyryl-CoA hydrolase deficiency (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HIBCH | HGNC:4908 | 3-hydroxyisobutyryl-CoA hydrolase deficiency | MONDO:0009603 | AR | Definitive"
    explanation: ClinGen assigns definitive validity to this autosomal recessive gene-disease relationship.
diagnosis:
- name: Molecular genetic confirmation
  description: >-
    The diagnosis is established by identifying biallelic pathogenic or likely
    pathogenic HIBCH variants in an individual with compatible clinical,
    biochemical, and imaging findings. If sequencing identifies only one
    variant, deletion/duplication-sensitive or broader genomic testing may be
    required.
  diagnosis_term:
    preferred_term: molecular genetic testing
    term:
      id: NCIT:C19770
      label: Molecular Analysis
    qualifiers:
    - predicate:
        preferred_term: has participant
        term:
          id: RO:0000057
          label: has participant
      value:
        preferred_term: HIBCH
        term:
          id: hgnc:4908
          label: HIBCH
  results: Biallelic pathogenic or likely pathogenic HIBCH variants establish the diagnosis.
  evidence:
  - reference: PMID:41264763
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The diagnosis of HIBCH deficiency is established in a proband with
      characteristic clinical, laboratory, and brain imaging findings and
      biallelic pathogenic variants in HIBCH identified by molecular genetic
      testing.
    explanation: GeneReviews identifies molecular detection of biallelic pathogenic variants as confirmatory.
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the targeted NGS testing is costly, and it can not identify possible
      pathogenic variants in deep intron regions and larger
      deletions/duplications.
    explanation: The cohort report identifies relevant limitations of targeted sequencing.
- name: Supportive biochemical testing
  description: >-
    Plasma or dried-blood-spot acylcarnitines and urine organic-acid or
    specialized thiol-conjugate testing can provide biochemical clues. Normal
    C4-OH or routine metabolites do not exclude the disease, and
    nonchromatographic C4-OH is not specific.
  diagnosis_term:
    preferred_term: diagnostic procedure
    term:
      id: NCIT:C18020
      label: Diagnostic Procedure
  results: >-
    Specific 3-hydroxyisobutyrylcarnitine, SCPC/SCPCM species, or
    2,3-dihydroxy-2-methylbutyrate can support suspicion but require molecular
    confirmation.
  evidence:
  - reference: PMID:26163321
    reference_title: "Metabolite studies in HIBCH and ECHS1 defects: Implications for screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      However, we observed normal hydroxy-C4 carnitine levels in one out of two
      dried blood spots collected after the neonatal period.
    explanation: Normal C4-OH can occur after the neonatal period.
  - reference: PMID:26163321
    reference_title: "Metabolite studies in HIBCH and ECHS1 defects: Implications for screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Increased hydroxy-C4 carnitine is therefore not specific for HIBCHD"
    explanation: The metabolite study directly states the C4-OH specificity limitation.
- name: HIBCH enzyme assay in cultured fibroblasts
  description: >-
    Specialized measurement of HIBCH activity in cultured skin fibroblasts can
    provide functional confirmation when molecular or biochemical findings are
    uncertain.
  diagnosis_term:
    preferred_term: diagnostic procedure
    term:
      id: NCIT:C18020
      label: Diagnostic Procedure
  results: Markedly decreased or absent HIBCH activity supports the diagnosis.
  evidence:
  - reference: PMID:24299452
    reference_title: HIBCH mutations can cause Leigh-like disease with combined deficiency of multiple mitochondrial respiratory chain enzymes and pyruvate dehydrogenase.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Fibroblast HIBCH activity was below detectable limits in both patients"
    explanation: Direct fibroblast testing established the functional enzyme defect in affected siblings.
- name: Brain MRI
  description: >-
    Brain MRI characterizes the Leigh-like pattern, especially bilateral
    pallidal or broader basal-ganglia lesions, but the imaging pattern is
    supportive rather than specific or confirmatory.
  diagnosis_term:
    preferred_term: magnetic resonance imaging procedure
    term:
      id: NCIT:C16809
      label: Magnetic Resonance Imaging
  results: Bilateral basal-ganglia lesions support a Leigh-spectrum presentation and direct etiologic testing.
  evidence:
  - reference: DOI:10.1038/s41439-023-00251-y
    reference_title: Leigh-like syndrome with progressive cerebellar atrophy caused by novel HIBCH variants
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Brain magnetic resonance imaging (MRI) shows bilateral lesions in the basal ganglia with/without brainstem involvement."
    explanation: The report summarizes the characteristic but nonspecific imaging pattern.
differential_diagnoses:
- name: ECHS1 deficiency
  disease_term:
    preferred_term: mitochondrial short-chain Enoyl-CoA hydratase 1 deficiency
    term:
      id: MONDO:0014563
      label: mitochondrial short-chain Enoyl-Coa hydratase 1 deficiency
  description: >-
    ECHS1 acts immediately upstream of HIBCH and can be clinically and
    biochemically very similar. Chromatographic detection of increased
    3-hydroxyisobutyrylcarnitine favors HIBCH deficiency, whereas many other
    urine intermediates overlap.
  distinguishing_features:
  - Increased specific 3-hydroxyisobutyrylcarnitine supports HIBCH deficiency over ECHS1 deficiency.
  - SCPC, SCPCM, and 2,3-dihydroxy-2-methylbutyrate can occur in both disorders.
  evidence:
  - reference: PMID:26163321
    reference_title: "Metabolite studies in HIBCH and ECHS1 defects: Implications for screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      With the exception of 3-hydroxyisobutyryl carnitine, the metabolite
      abnormalities were essentially the same as those observed in patients
      with ECHS1 mutations
    explanation: The metabolite study supplies a direct biochemical discriminator.
- name: Primary pyruvate dehydrogenase deficiency
  disease_term:
    preferred_term: pyruvate dehydrogenase deficiency
    term:
      id: MONDO:0019169
      label: pyruvate dehydrogenase deficiency
  description: >-
    HIBCH deficiency can present with secondary PDH-complex deficiency and a
    Leigh-like phenotype. Molecular and HIBCH-specific biochemical testing
    distinguish the secondary finding from a primary PDH disorder.
  evidence:
  - reference: PMID:24299452
    reference_title: HIBCH mutations can cause Leigh-like disease with combined deficiency of multiple mitochondrial respiratory chain enzymes and pyruvate dehydrogenase.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      HIBCH deficiency, a disorder of valine catabolism, is a novel cause of
      the multiple mitochondrial dysfunctions syndrome, and should be considered
      in the differential diagnosis of patients presenting with multiple RC
      deficiencies and/or pyruvate dehydrogenase deficiency.
    explanation: The sibling study explicitly identifies the PDH/respiratory-chain diagnostic context.
- name: Other Leigh syndrome spectrum etiologies
  disease_term:
    preferred_term: Leigh syndrome
    term:
      id: MONDO:0009723
      label: Leigh syndrome
  description: >-
    Leigh syndrome is a presentation umbrella that HIBCH deficiency can cause,
    rather than a mutually exclusive diagnosis. Other mitochondrial and nuclear
    etiologies must be distinguished through molecular testing and
    disease-specific biochemical clues.
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Applying next-generation sequencing, we identified eight patients with
      HIBCH mutations from our cohort of 181 cases of genetically diagnosed
      Leigh/Leigh-like syndrome.
    explanation: HIBCH deficiency was identified as one molecular cause within a Leigh/Leigh-like cohort.
- name: Propionic and methylmalonic acidemias
  description: >-
    Propionate-pathway disorders can share 2,3-dihydroxy-2-methylbutyrate and
    acryloyl-CoA-related metabolites. SCPC/SCPCM patterns, acylcarnitines,
    organic acids, and molecular testing distinguish these disorders.
  evidence:
  - reference: PMID:26163321
    reference_title: "Metabolite studies in HIBCH and ECHS1 defects: Implications for screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The metabolites derived from acryloyl-CoA were also increased in patients
      with inborn errors of propionyl-CoA metabolism
    explanation: The metabolite study documents overlap with propionyl-CoA disorders.
  - reference: PMID:37309295
    reference_title: "Acyl-CoA dehydrogenase substrate promiscuity: Challenges and opportunities for development of substrate reduction therapy in disorders of valine and isoleucine metabolism."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Toxicity of accumulating substrates is a significant problem in several
      disorders of valine and isoleucine degradation notably short-chain
      enoyl-CoA hydratase (ECHS1 or crotonase) deficiency,
      3-hydroxyisobutyryl-CoA hydrolase (HIBCH) deficiency, propionic acidemia
      (PA), and methylmalonic aciduria (MMA).
    explanation: The review places HIBCH, ECHS1, propionic acidemia, and methylmalonic aciduria in an overlapping metabolic context.
treatments:
- name: Valine-restricted diet
  therapeutic_modality: BEHAVIORAL
  description: >-
    Valine restriction is the expert-recommended targeted dietary approach,
    intended to reduce substrate flux into the impaired pathway. Evidence is
    limited to small uncontrolled reports and expert experience; no consensus
    protocol, controlled efficacy estimate, or universal age-specific valine
    target is established.
  treatment_term:
    preferred_term: dietary intervention
    term:
      id: NCIT:C15447
      label: Dietary Intervention
  target_mechanisms:
  - target: Reactive valine-derived intermediate accumulation
    treatment_effect: INHIBITS
    description: Reduced valine intake is intended to decrease formation of reactive valine-derived intermediates.
    evidence:
    - reference: PMID:41264763
      reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "MANAGEMENT: Targeted therapy: Valine-restricted diet."
      explanation: GeneReviews identifies valine restriction as mechanism-targeted care.
  evidence:
  - reference: PMID:41264763
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      MANAGEMENT: Targeted therapy: Valine-restricted diet. As seen in other
      metabolic disorders, treatment using special formulas (medical food) can
      be implemented successfully via oral route in individuals diagnosed
      within the first few months of life.
    explanation: GeneReviews describes practical implementation while not supplying a controlled efficacy estimate.
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There is currently no consensus on HIBCH deficiency treatment approaches.
      A low-valine, carbohydrate-rich diet may be effective
    explanation: The clinical cohort explicitly identifies lack of consensus and uses cautious efficacy language.
- name: Prevention of catabolism
  description: >-
    Avoidance of prolonged fasting and individualized sick-day planning are
    intended to reduce catabolic stress. Acute illness management should be
    directed by a metabolic specialist; the cached evidence does not define a
    validated universal emergency protocol.
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_mechanisms:
  - target: Illness-associated acute neurometabolic decompensation
    treatment_effect: INHIBITS
    description: Preventing catabolism is intended to reduce illness-associated decompensation risk.
  evidence:
  - reference: PMID:41264763
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "prevent catabolism"
    explanation: GeneReviews includes prevention of catabolism among management precautions.
- name: Symptom-directed supportive care
  description: >-
    Multidisciplinary care addresses development, feeding, spasticity,
    epilepsy, movement disorder, vision, hearing, mobility, and family support.
    These interventions treat manifestations rather than the enzymatic defect.
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
  evidence:
  - reference: PMID:41264763
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Supportive care: Developmental and educational support; feeding therapy
      with gastrostomy tube as needed; standard treatments for spasticity and
      epilepsy; treatment of movement disorder per movement disorder
      specialist; management of ocular issues per ophthalmologist with low
      vision services as needed
    explanation: GeneReviews defines concrete multidisciplinary supportive care.
- name: Avoidance of selected mitochondrial and dietary stressors
  description: >-
    GeneReviews conditionally advises avoiding sodium valproate when possible
    because of secondary mitochondrial abnormalities, careful anesthesia use,
    and avoidance of prolonged propofol. It more directly advises against
    ketogenic or modified Atkins diets and lists triheptanoin as
    contraindicated; these are expert precautions rather than comparative-trial
    findings.
  treatment_term:
    preferred_term: medical action avoidance
    term:
      id: NCIT:C15900
      label: Lifestyle Therapy
  evidence:
  - reference: PMID:41264763
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Due to secondary mitochondrial abnormalities it may be beneficial to
      avoid sodium valproate if possible; consider anesthesia use carefully;
      avoid prolonged propofol use
    explanation: GeneReviews uses conditional wording for valproate and peri-anesthetic precautions.
  - reference: PMID:41264763
    reference_title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      ketogenic / modified Atkins diets should be avoided due to potential side
      effects; triheptanoin is contraindicated due to the potential increase in
      propionyl-CoA
    explanation: GeneReviews provides the stronger diet and triheptanoin avoidance language.
discussions:
- discussion_id: gap_hibch_reactive_metabolite_mechanism
  prompt: >-
    Which methacrylyl-CoA-derived protein modifications drive human neural
    injury, and why are secondary PDH and respiratory-chain defects variable?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Reactive valine-derived intermediate accumulation
  - pathophysiology#Variable secondary PDH and respiratory-chain dysfunction
  rationale: >-
    Human metabolites support reactive-intermediate accumulation, but thiol
    adduction, glutathione depletion, lysine methacrylation, mitochondrial
    dysfunction, and selective basal-ganglia vulnerability have not been joined
    into a validated human causal chain.
  evidence:
  - reference: PMID:24299452
    reference_title: HIBCH mutations can cause Leigh-like disease with combined deficiency of multiple mitochondrial respiratory chain enzymes and pyruvate dehydrogenase.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The index case had deficiencies of multiple RC enzymes and PDHc in
      skeletal muscle and fibroblasts respectively, but these were normal in his
      younger brother.
    explanation: Affected siblings demonstrate variable secondary mitochondrial findings.
  - reference: PMID:40056416
    reference_title: Ectopic protein lysine methacrylation contributes to defects caused by loss of HIBCH or ECHS1.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We propose that ectopic Kmea modification mediates the defects caused by HIBCH- or ECHS1-deficiency."
    explanation: The newest methacrylation model remains an experimental proposal.
- discussion_id: gap_hibch_valine_restriction
  prompt: >-
    What valine targets, age at initiation, monitoring strategy, and nutritional
    safeguards provide meaningful long-term clinical benefit?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - treatments#Valine-restricted diet
  rationale: >-
    Valine restriction is mechanism-directed and recommended by experts, but
    published outcomes are uncontrolled, regimens vary, and natural history is
    heterogeneous.
  evidence:
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "There is currently no consensus on HIBCH deficiency treatment approaches."
    explanation: The cohort review directly identifies the sparse and heterogeneous treatment evidence.
- discussion_id: gap_hibch_biomarker_and_screening_validation
  prompt: >-
    Can isomer-resolved C4-OH, SCPC/SCPCM species, or a combined panel achieve
    adequate sensitivity and specificity for diagnosis or newborn screening?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - biochemical#3-hydroxyisobutyrylcarnitine (C4-OH)
  - biochemical#Urinary S-(2-carboxypropyl)cysteine and its carnitine ester
  - biochemical#Urinary S-(2-carboxypropyl)cysteamine
  - diagnosis#Supportive biochemical testing
  rationale: >-
    C4-OH is neither universal nor specific without isomer separation, while
    promising thiol-conjugate markers have very small selected denominators and
    require specialized methods. Screening thresholds and clinical benefit are
    not validated.
  evidence:
  - reference: PMID:26163321
    reference_title: "Metabolite studies in HIBCH and ECHS1 defects: Implications for screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Increased hydroxy-C4 carnitine is therefore not specific for HIBCHD"
    explanation: The paper identifies both the limitation and a candidate combined approach.
  - reference: PMID:33762937
    reference_title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SCPCM seems to be more speci fic for disease diagnosis, but more samples are needed for verification."
    explanation: The clinical series explicitly calls for more marker validation.
- discussion_id: interpretation_hibch_variant_location_survival
  prompt: >-
    Can variant position or residual HIBCH activity reliably predict severity
    and survival?
  kind: INTERPRETATION
  status: OPEN
  attaches_to:
  - genetic#HIBCH pathogenic variants
  - progression#Variable survival and long-term disability
  rationale: >-
    A combined ECHS1/HIBCH natural-history analysis reported a survival
    association with HIBCH variant location, but the ultra-rare sample and
    retrospective ascertainment do not support deterministic counseling.
  evidence:
  - reference: DOI:10.1002/jimd.12288
    reference_title: "Delineating the neurological phenotype in children with defects in the <scp><i>ECHS1</i></scp> or <scp><i>HIBCH</i></scp> gene"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among all 89 cases, we observed a longer survival in HIBCH compared to SCEH patients, and in HIBCH patients carrying homozygous mutations on the protein surface compared to those with variants inside/near the catalytic region."
    explanation: The study reports an exploratory variant-location survival association.
references:
- reference: CGGV:assertion_26621ace-7c6b-4a1c-8286-02c4cb8a1544-2019-11-07T222437.403Z
  title: "HIBCH / 3-hydroxyisobutyryl-CoA hydrolase deficiency (Definitive)"
- reference: PMID:24299452
  title: HIBCH mutations can cause Leigh-like disease with combined deficiency of multiple mitochondrial respiratory chain enzymes and pyruvate dehydrogenase.
- reference: PMID:26163321
  title: "Metabolite studies in HIBCH and ECHS1 defects: Implications for screening."
- reference: PMID:33762937
  title: "Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome."
- reference: PMID:37309295
  title: "Acyl-CoA dehydrogenase substrate promiscuity: Challenges and opportunities for development of substrate reduction therapy in disorders of valine and isoleucine metabolism."
- reference: PMID:40056416
  title: Ectopic protein lysine methacrylation contributes to defects caused by loss of HIBCH or ECHS1.
- reference: PMID:41264763
  title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
  tags:
  - GeneReviews
- reference: DOI:10.1002/jimd.12288
  title: "Delineating the neurological phenotype in children with defects in the <scp><i>ECHS1</i></scp> or <scp><i>HIBCH</i></scp> gene"
- reference: DOI:10.1038/s41439-023-00251-y
  title: Leigh-like syndrome with progressive cerebellar atrophy caused by novel HIBCH variants
- reference: DOI:10.1159/000508728
  title: 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency in a Turkish Child with a Novel HIBCH Gene Mutation and Literature Review
- reference: DOI:10.24911/jbcgenetics.183-1722167696
  title: "Characterization of 3-Hydroxyisobutyryl-Coa Hydrolase (HIBCH) Deficiency in Bahrain: A Retrospective Cohort Study"
📚

References & Deep Research

References

11
HIBCH / 3-hydroxyisobutyryl-CoA hydrolase deficiency (Definitive)
No top-level findings curated for this source.
HIBCH mutations can cause Leigh-like disease with combined deficiency of multiple mitochondrial respiratory chain enzymes and pyruvate dehydrogenase.
No top-level findings curated for this source.
Metabolite studies in HIBCH and ECHS1 defects: Implications for screening.
No top-level findings curated for this source.
Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome.
No top-level findings curated for this source.
Acyl-CoA dehydrogenase substrate promiscuity: Challenges and opportunities for development of substrate reduction therapy in disorders of valine and isoleucine metabolism.
No top-level findings curated for this source.
Ectopic protein lysine methacrylation contributes to defects caused by loss of HIBCH or ECHS1.
No top-level findings curated for this source.
3-Hydroxyisobutyryl-CoA Hydrolase Deficiency.
No top-level findings curated for this source.
Delineating the neurological phenotype in children with defects in the <scp><i>ECHS1</i></scp> or <scp><i>HIBCH</i></scp> gene
No top-level findings curated for this source.
Leigh-like syndrome with progressive cerebellar atrophy caused by novel HIBCH variants
No top-level findings curated for this source.
3-Hydroxyisobutyryl-CoA Hydrolase Deficiency in a Turkish Child with a Novel HIBCH Gene Mutation and Literature Review
No top-level findings curated for this source.
Characterization of 3-Hydroxyisobutyryl-Coa Hydrolase (HIBCH) Deficiency in Bahrain: A Retrospective Cohort Study
No top-level findings curated for this source.

Deep Research

2
Asta
Asta Literature Retrieval: Pathophysiology and clinical mechanisms of 3-hydroxyisobutyryl-CoA hydrolase deficiency. Core disease mechanisms, mol...
Asta Scientific Corpus Retrieval 20 citations 2026-04-15T19:37:45.204012

Asta Literature Retrieval: Pathophysiology and clinical mechanisms of 3-hydroxyisobutyryl-CoA hydrolase deficiency. Core disease mechanisms, mol...

This report is retrieval-only and is generated directly from Asta results.

  • Papers retrieved: 20
  • Snippets retrieved: 20

Relevant Papers

[1] Changes in Serum Proteomic Profiles at Different Stages of Pregnancy Toxemia in Goats

  • Authors: M. Uzti̇mür, C. N. Ünal, Gurler Akpinar
  • Year: 2025
  • Venue: Journal of Veterinary Internal Medicine
  • URL: https://www.semanticscholar.org/paper/4b9c488b5dbd65d7b26fd2ad9aed70e8c4b59942
  • DOI: 10.1111/jvim.70139
  • PMID: 40492724
  • PMCID: 12150350
  • Summary: Understanding the serum proteome profiles of goats with pregnancy toxemia might help identify the proteomes and pathways responsible for the development of this disease and improve diagnosis and treatment.
  • Evidence snippets:
  • Snippet 1 (score: 0.486) > The pathophysiology and progression of this disease are not fully understood. > Traditional biomedical research has focused on the analysis of single genes, proteins, metabolites, or metabolic pathways in diseases. This molecular reductionist approach is based on the assumption that identifying genetic variations and molecular components will lead to new treatments for diseases [13][14][15][16]. However, many diseases are complex and multifactorial, and in order to determine the phenotype of such diseases, it is necessary to understand the changes that occur in more than one gene, pathway, protein, or metabolite at the cellular, tissue, and organismal levels [17][18][19]. Therefore, in recent years, proteomics, as one field of multi-omics technologies, has helped in evaluating the complex pathogenetic mechanisms of different diseases from a broad perspective and has made substantial contributions [20,21]. In veterinary medicine, proteomic analysis of metabolic diseases such as ketosis [16], hypocalcemia [22], and fatty liver [23] in dairy cows has contributed valuable insights for the definition of new pathophysiological pathways and new diagnosis and treatment protocols for these diseases. The proteomic approach can contribute importantly to a broad and detailed understanding of the changes that occur at the organismal level associated with the increase in BHBA concentration in goats with pregnancy toxemia. Our aim was to evaluate the serum protein profiles of goats with SPT or CPT using proteomic techniques to determine the proteomic profiles of these animals and to identify the relevant pathophysiological mechanisms.

[2] Pediatric Paroxysmal Exercise-Induced Neurological Symptoms: Clinical Spectrum and Diagnostic Algorithm

  • Authors: F. R. Danti, F. Invernizzi, I. Moroni, B. Garavaglia, N. Nardocci et al.
  • Year: 2021
  • Venue: Frontiers in Neurology
  • URL: https://www.semanticscholar.org/paper/92b36a8a32d63b0a6cb99345cd885e3a6018171c
  • DOI: 10.3389/fneur.2021.658178
  • PMID: 34140924
  • PMCID: 8203909
  • Citations: 4
  • Summary: The clinical, genetic, pathophysiologic, and therapeutic landscape of paroxysmal exercise induced neurological symptoms is reviewed, focusing on phenomenology and differential diagnosis.
  • Evidence snippets:
  • Snippet 1 (score: 0.482) > PED has been recently associated with the deficiency of a number of mitochondrial enzymes involved in energy production and branched-chain amino acids (BCAA; leucine, isoleucine, and valine) catabolism. They include Pyruvate dehydrogenase (PDH) complex, short-chain enoyl-CoA hydratase (ECSH1) and 3-Hydroxyisobutyryl-CoA hydrolase (HIBCH) (Figure 2) (33, 34). > PDH complex catalyses the oxidative decarboxylation of pyruvate with the production of acetyl-CoA; therefore, it connects the glycolytic pathway to the Krebs cycle and plays a central role in glucose metabolism in fed and fasting states. PDH complex is composed of three catalytic subunits: pyruvate dehydrogenase (PDH; E1, a heterotetramer of 2 subunits encoded by PDHA1 and PDHB1 genes), dihydrolipoamide acetyltransferase (E2, encoded by DLAT gene), and dihydrolipoamide dehydrogenase (E3, encoded by DLD gene), and of an additional component, the E3-binding protein (encoded by PDHX1) (35, 36). PDHA1, DLAT, and PDHX1 mutations have been linked to continuously expanding phenotypes inherited with X-linked (PDHA1 mutations, representing the main cause of PDH deficiency) or autosomal recessive pattern (DLAT and PDHX1 mutation). Clinical findings range from severe infantile lactic acidosis to milder chronic neurological disorders including intermittent and recurrent acute neurological symptoms such as episodic ataxia, peripheral weakness, and movement disorders such as PED and PNKD (36-38). In few patients recurrent dystonic or hemidystonic attacks have been described; they are triggered by prolonged walking and running and occur as a unique clinical manifestation or within complex neurological phenotypes (39-41).

[3] Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome

  • Authors: Junling Wang, Zhimei Liu, Manting Xu, Xiaodi Han, C. Ren et al.
  • Year: 2021
  • Venue: Frontiers in Pharmacology
  • URL: https://www.semanticscholar.org/paper/d344b1c2d00932f15f1b993fbd15d7852ed52b06
  • DOI: 10.3389/fphar.2021.605803
  • PMID: 33762937
  • PMCID: 7982470
  • Citations: 14
  • Influential citations: 3
  • Summary: The purpose of this study was to analyze the phenotypic spectrum, follow-up results, metabolites, and genotypes of patients with HIBCH deficiency presenting with Leigh/Leigh-like syndrome and explore specific metabolites related to disease diagnosis and prognosis through retrospective and longitudinal studies.
  • Evidence snippets:
  • Snippet 1 (score: 0.472) > 3-Hydroxyisobutyryl-CoA hydrolase (HIBCH, NM_014362.3) gene mutation can cause HIBCH deficiency, leading to Leigh/Leigh-like disease. To date, few case series have investigated the relationship between metabolites and clinical phenotypes or the effects of treatment, although 34 patients with HIBCH mutations from 27 families have been reported. The purpose of this study was to analyze the phenotypic spectrum, follow-up results, metabolites, and genotypes of patients with HIBCH deficiency presenting with Leigh/Leigh-like syndrome and explore specific metabolites related to disease diagnosis and prognosis through retrospective and longitudinal studies. Applying next-generation sequencing, we identified eight patients with HIBCH mutations from our cohort of 181 cases of genetically diagnosed Leigh/Leigh-like syndrome. Six novel HIBCH mutations were identified: c.977T>G [p.Leu326Arg], c.1036G>T [p.Val346Phe], c.750+1G>A, c.810-2A>C, c.469C>T [p.Arg157], and c.236delC [p.Pro79Leufs5]. The Newcastle Pediatric Mitochondrial Disease Scale (NPMDS) was employed to assess disease progression and clinical outcomes. The non-invasive approach of metabolite analysis showed that levels of some were associated with clinical phenotype severity. Five (5/7) patients presented with elevated C4-OH in dried blood spots, and the level was probably correlated with the NPMDS scores during the peak disease phase. 2,3-Dihydroxy-2-methylbutyrate in urine was elevated in six (6/7) patients and elevated S-(2-caboxypropyl)cysteamine in urine was found in three patients (3/3). The median age at initial presentation was 13 months (8–18 months), and the median follow-up was 2.3 years (range 1.3–7.2 years). We summarized and compared with all reported patients with HIBCH mutations. The most prominent clinical manifestations were developmental regression/

[4] Identification of HIBCH and MGME1 as Mitochondrial Dynamics‐Related Biomarkers in Alzheimer's Disease Via Integrated Bioinformatics Analysis

  • Authors: Hailong Li, Fei Feng, Shou-pin Xie, Yanping Ma, Yafeng Wang et al.
  • Year: 2025
  • Venue: IET Systems Biology
  • URL: https://www.semanticscholar.org/paper/77185e17e1f3375b9031c9851afadaced3eecc7a
  • DOI: 10.1049/syb2.70018
  • PMID: 40286336
  • PMCID: 12033025
  • Citations: 2
  • Summary: HIBCH and MGME1 are promising diagnostic biomarkers for AD with AUC values of 0.73 and 0.74 and Mechanistically, miR‐922 was experimentally validated to directly bind MGME1 3′UTR.
  • Evidence snippets:
  • Snippet 1 (score: 0.471) > In summary, MGME1 deficiency may impair mtDNA repair, leading to mitochondrial genome instability and bioenergetic failure. These findings collectively nominate MGME1 as a promising AD biomarker, with therapeutic targeting of MGME1 potentially mitigating pathological mtDNA-mediated neuroinflammation. The 3-hydroxyisobutyryl-coenzyme A (CoA) hydrolase (HIBCH) enzyme, which is encoded by HIBCH, is involved in significant stages of valine degradation. Neurological symptoms resulting from uncommon metabolic dysfunctions are caused by HIBCH deficit (HIBCHD) [27]. An uncommon condition of the mitochondrial valine metabolism known as 3-Hydroxyisobutyryl-CoA hydrolase (HIBCH) deficiency can cause organic aciduria, motor delay, hypotonia, ataxia, dystonia, seizures, poor eating and developmental regression or delay [4]. Both HIBCH deficiency and Leigh/ Leigh-like illness are caused by mutations in the 3-Hydroxyisobutyryl-CoA hydrolase (HIBCH) gene [4]. Leighlike disease and HIBCH deficiency can be caused by mutations in the 3-Hydroxyisobutyryl-CoA hydrolase (HIBCH) gene [4]. Neuroimaging results show abnormalities in signals in the cerebral peduncles and globus pallidi, which are located in the deep grey matter [4]. The findings of neuroimaging reveal anomalies in signals within the deep grey matter, specifically in the cerebral peduncles and globus pallidi [28,29]. It was discovered that HIBCH is one of the proteins that is overexpressed in malignancies, such as ovarian tumours, and that is expressed differentially in mitochondria [30], Blocking 3hydroxyisobutyryl-CoA hydrolase (HIBCH) to stop the breakdown of valine resulted in decreased intracellular succinate, a decrease in the development of cancerous prostate cells, and impaired cellular respiration [31].

[5] HIBCH mutations can cause Leigh-like disease with combined deficiency of multiple mitochondrial respiratory chain enzymes and pyruvate dehydrogenase

  • Authors: S. Ferdinandusse, H. Waterham, S. Heales, Garry K. Brown, I. Hargreaves et al.
  • Year: 2013
  • Venue: Orphanet Journal of Rare Diseases
  • URL: https://www.semanticscholar.org/paper/54d1e94c64b6353cdcf9e97e451e68839e044cd0
  • DOI: 10.1186/1750-1172-8-188
  • PMID: 24299452
  • PMCID: 4222069
  • Citations: 80
  • Influential citations: 7
  • Summary: HIBCH deficiency, a disorder of valine catabolism, is a novel cause of the multiple mitochondrial dysfunctions syndrome, and should be considered in the differential diagnosis of patients presenting with multiple RC deficiencies and/or pyruvate dehydrogenase deficiency.
  • Evidence snippets:
  • Snippet 1 (score: 0.470) > Mitochondrial disorders affect approximately 1 in 5000 births, and are clinically, biochemically and genetically heterogeneous [1]. Combined deficiency of multiple respiratory chain (RC) enzymes is one of the most frequent findings in children with suspected mitochondrial disease, representing approximately 30% of cases in whom a biochemical abnormality is identified. Approximately 50% of patients with multiple RC deficiencies have impaired replication or maintenance of the mitochondrial DNA (mtDNA), leading to progressive depletion of mtDNA [2] or accumulation of multiple mtDNA deletions. The remaining~50% of cases have heterogeneous underlying causes, including mitochondrial or nuclear-encoded defects of mitochondrial protein synthesis [3] and the multiple mitochondrial dysfunctions syndrome, in which the activity of PDHc is also impaired [4][5][6]. Defects in mtDNA repair, maintenance or translation result in combined deficiency of complexes I, III and IV (i.e. complexes that contain mtDNA-encoded subunits) whereas the multiple mitochondrial dysfunctions syndrome usually affects complexes containing iron-sulphur (Fe-S) clusters (complexes I, II and III) as well as PDHc. > Neurological features of cerebral organic acidurias (disorders of degradation of the carbon skeleton of amino acids) can be clinically and radiologically indistinguishable from mitochondrial encephalomyopathies caused by primary RC deficiencies; seizures, neurological regression and bilateral symmetrical basal ganglia lesions may occur in both groups of disorders [7][8][9][10]. 3-Hydroxyisobutyryl-CoA hydrolase (HIBCH) is a mitochondrial enzyme that catalyses the fifth step of valine catabolism, the conversion of 3-hydroxy-isobutyryl-CoA to 3-hydroxyisobutyrate ( Figure 1a). HIBCH deficiency has previously been reported in only two patients [11,12]. We now describe two new genetically confirmed cases (siblings), one of whom presented with combined defects of multiple RC enzymes and the pyruvate dehydrogenase complex (PDHc). This potentially represents a new disease mechanism mimicking the multiple mitochondrial dysfunctions syndrome, namely degradation of multiple enzymes resulting from accumulation of a toxic metabolite methacrylyl

[6] Current and Emerging Issues in Familial Hypobetalipoproteinemia-related Steatotic Liver Diseases

  • Authors: Tian-Wen Lou, Tian-Yi Ren, Jian-gao Fan
  • Year: 2025
  • Venue: Journal of Clinical and Translational Hepatology
  • URL: https://www.semanticscholar.org/paper/cf1c6534ba154bbb870b421a4e111acb62023405
  • DOI: 10.14218/JCTH.2025.00360
  • PMID: 41473260
  • PMCID: 12745358
  • Summary: Challenges include insufficient diagnosis, sparse epidemiological data, and unclear disease progression; enhanced genetic testing, mechanistic research, and longitudinal studies are critical to improving diagnosis, risk assessment, and therapies for FHBL-associated liver disease.
  • Evidence snippets:
  • Snippet 1 (score: 0.454) > ecent advances in molecular genetics have refined our understanding of APOB-related pathophysiology, yet critical questions remain unanswered, particularly regarding why some FHBL patients develop progressive liver disease while others remain stable, and what the specific mechanisms and molecular pathways are for the occurrence and development of liver disease. > This review aims to refocus attention on the hepatic aspects of FHBL by (i) summarizing current knowledge of molecular genetics, (ii) analyzing the spectrum and progression of liver disease in affected individuals, (iii) exploring mechanistic hypotheses that may explain liver disease, and (iv) outlining the clinical treatment plan. We aim to establish FHBL not only as a disorder of lipid metabolism but also as a valuable window into the pathogenesis of steatotic liver disease.

[7] HMG–CoA Lyase Deficiency

  • Authors: B. Puisac, María Arnedo, M. Gil-Rodríguez, E. Teresa, Á. Pié et al.
  • Year: 2011
  • Venue: Unknown venue
  • URL: https://www.semanticscholar.org/paper/ffd0bf7b7af0c6b88ada7c59a737d4d83e10c3b2
  • DOI: 10.5772/20252
  • Citations: 4
  • Summary: A recent study of differential expression of human HL in liver, pancreas, testis, heart, skeletal muscle and brain that can help us to understand the consequences of this deficiency and draw a map of incidence.
  • Evidence snippets:
  • Snippet 1 (score: 0.449) > The HMG-CoA lyase (HL) deficiency or 3-hydroxy-3-methylglutaric aciduria (MIM 246450) is an inborn error of intermediary metabolism that was first described in 1976 by Faull et al (Faull et al., 1976). Because its clinical manifestations, it has been included within the Sudden Infant Death Syndrome (Wilson et al., 1984). At present, it is considered a rare disease (<1/100,000 live neonates) that should be diagnosed at early age because there is a simple and effective treatment (Watson et al., 2006). HL is a mitochondrial enzyme that catalyzes the cleavage of HMG-CoA to acetyl-CoA and acetoacetate, which is the common final step of ketogenesis and leucine catabolism (Figure 1). Patients with this disease suffer on the one hand, the absence of ketone bodies as alternative energy source of glucose and on the other hand, the accumulation of toxic metabolites of leucine catabolism. The most frequently affected organs are the liver and the brain, but the pancreas and the heart can also be involved. This chapter discusses a recent study of differential expression of human HL in liver, pancreas, testis, heart, skeletal muscle and brain that can help us to understand the consequences of this deficiency (Puisac et al., 2010). It is an autosomal recessive disease caused by mutations in the HMGCL gene. The study of these mutations and patients origin helps to draw a map of incidence in which three countries stand out for their high frequency: Saudi Arabia (Ozand et al., 1992), Spain and Portugal (Menao et al., 2009). At present, the functional study of missense mutations is possible thanks to the knowledge of the structure (Fu et al., 2006) and mechanism of the enzyme (Fu et al., 2010) and also by the development of a method of simple and efficient expression of the protein (Menao et al., 2009). Finally, despite the current knowledge of the disease, genotype-phenotype correlations are difficult to establish.

[8] Global and Targeted Metabolomics for Revealing Metabolomic Alteration in Niemann-Pick Disease Type C Model Cells

  • Authors: Masahiro Watanabe, Masamitsu Maekawa, Keitaro Miyoshi, Toshihiro Sato, Yu Sato et al.
  • Year: 2024
  • Venue: Metabolites
  • URL: https://www.semanticscholar.org/paper/27c7aa8f74e2997a59b92b38aec1fb9ff9cbb608
  • DOI: 10.3390/metabo14100515
  • PMID: 39452896
  • PMCID: 11509386
  • Citations: 2
  • Summary: Several metabolite characteristics of Niemann-Pick disease type C that may fluctuate in a cellular model of the disease are identified using both global and targeted metabolomic analyses by liquid chromatography/tandem mass spectrometry.
  • Evidence snippets:
  • Snippet 1 (score: 0.444) > Background: Niemann-Pick disease type C (NPC) is an inherited disorder characterized by a functional deficiency of cholesterol transport proteins. However, the molecular mechanisms and pathophysiology of the disease remain unknown. Methods: In this study, we identified several metabolite characteristics of NPC that may fluctuate in a cellular model of the disease, using both global and targeted metabolomic analyses by liquid chromatography/tandem mass spectrometry (LC-MS/MS). Three cell lines, HepG2 cells (wild-type[WT]) and two NPC model HepG2 cell lines in which NPC1 was genetically ablated (knockout [KO]1 and KO2), were used for metabolomic analysis. Data were subjected to enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Results: The enrichment analysis of global metabolomics revealed that 8 pathways in KO1 and 16 pathways in KO2 cells were notably altered. In targeted metabolomics for 15 metabolites, 4 metabolites in KO1 and 10 metabolites in KO2 exhibited statistically significant quantitative changes in KO1 or KO2 relative to WT. Most of the altered metabolites were related to creatinine synthesis and cysteine metabolism pathways. Conclusions: In the future, our objective will be to elucidate the relationship between these metabolic alterations and pathophysiology.

[9] 18O-assisted dynamic metabolomics for individualized diagnostics and treatment of human diseases

  • Authors: E. Nemutlu, Song Zhang, N. Juranic, A. Terzic, S. Macura et al.
  • Year: 2012
  • Venue: Croatian Medical Journal
  • URL: https://www.semanticscholar.org/paper/880f053c7f060db4b990e447d0a22c4b69372ddb
  • DOI: 10.3325/cmj.2012.53.529
  • PMID: 23275318
  • PMCID: 3541579
  • Citations: 28
  • Summary: The potential use of dynamic phosphometabolomic platform for disease diagnostics currently under development at Mayo Clinic is described and discussed briefly.
  • Evidence snippets:
  • Snippet 1 (score: 0.436) > Living cells represent an integrated and interacting network of genes, transcripts, proteins, small signaling molecules, and metabolites that define cellular phenotype and function. Traditionally the focus of biomedical research was on individual genes, single protein targets, single metabolites, and metabolic or signaling pathways. This "molecular reductionist" paradigm was based on the assumption that identifying genetic variations and molecular components would lead to discovery of cures for human diseases. However, most of diseases are complex and multi-factorial and the disease phenotype is determined by the alterations of multiple genes, pathways, proteins and metabolites (at cellular, tissue, and organismal levels). Therefore, an integrated "omics" approach is more viable direction for uncovering alterations in metabolic networks, disease mechanisms, and mechanisms of drug effects. > Recent advent of large-scale metabolomics and fluxomic (metabolite dynamics and metabolic flux analysis) completed the "omics revolution" (Figure 1), where genomics, transcriptomics, proteomics, metabolomics, and fluxomics all together complement phenotype determination of living organism. Such integrated "omics" cascades provide a framework for advances in system and network biology, integrative physiology, and system medicine as well as system pharmacology and regenerative medicine. Noteworthy is the "reverse omic" approach or "metabolomicsinformed pharmacogenomics, " where discovery of specific metabolite changes have led to discovery of genetic alterations (2). Therefore, bringing new "omics" technologies to clinical practice will improve disease diagnostics and treatment by targeting drugs and procedures for each unique transcriptomic and metabolomic profiles.

[10] Short-chain enoyl-CoA hydratase deficiency causes prominent ketoacidosis with normal plasma lactate levels: A case report

  • Authors: Madoka Uesugi, Jun Mori, S. Fukuhara, N. Fujii, Tadaki Omae et al.
  • Year: 2020
  • Venue: Molecular Genetics and Metabolism Reports
  • URL: https://www.semanticscholar.org/paper/872b6da3f3bccf1ecdc81939f3fa8209fb3263c4
  • DOI: 10.1016/j.ymgmr.2020.100672
  • PMID: 33163364
  • PMCID: 7606867
  • Citations: 8
  • Influential citations: 1
  • Summary: A 7-month-old boy with Short-chain enoyl-CoA hydratase (ECHS1) deficiency concomitant with prominent ketoacidosis, and no elevation in plasma lactate levels is reported, expanding the understanding of the multiple symptoms of ECHS1 deficiency and emphasizing the importance of genetic testing for inborn errors of metabolism to initiate early treatment.
  • Evidence snippets:
  • Snippet 1 (score: 0.431) > ECHS1 is a mitochondrial enzyme that catalyzes reactions in multiple metabolic pathways, such as fatty acid ß oxidation and degradation of branched-chain amino acids (valine, leucine, and isoleucine). ECHS1 deficiency was first reported in Leigh syndrome by Peters in 2014 [1]. Since then, ~50 cases of ECHS1 deficiency have been reported. The symptoms and findings of ECHS1 deficiency vary and the frequency of ECHS1 deficiency is rare. Even patients with identical genotypes have different symptoms. The main pathophysiology of ECHS1 deficiency involves the accumulation of toxic intermediate metabolites, such as methacrylyl-CoA, in the mitochondria in the valine catabolic pathway. Patients with ECHS1 deficiency have characteristic symptoms, such as severely delayed psychomotor development, nystagmus, hyperlactatemia, and brain lesions in the basal ganglia, with metabolic acidosis and variable ketosis. This case report is based on a 7-month-old boy with ECHS1 deficiency and chief complaints of conjugate deviation and hypotonia. The findings upon examination of the patient were: 1) remarkable ketoacidosis and 2) normal levels of lactate in the blood and cerebrospinal fluid. > The 3-hydroxyisobutyryl-CoA hydrolase gene (HIBCH) is located downstream of ECHS1 in the valine metabolic pathway. Thus, patients with ECHS1 deficiency show symptoms similar to those in patients with a deficiency of HIBCH. Patients with HIBCH deficiency exhibit marked ketoacidosis during stress conditions, such as fever. This can be attributed to the enhanced supply of ATP to the brain owing to fatty acid ß oxidation. In contrast, ketoacidosis is not always observed with patients with ECHS1 deficiency. Some patients with ECHS1 deficiency have ketoacidosis [4], but some patients with ECHS1 deficiency do not present with prominent ketoacidosis due to the impairment of short-chain fatty acid β oxidation and inability to produce ketone bodies [5]. It has recently been reported that ECHS1 is less involved in isoleucine metabolism and fatty acid ß oxidation [7].

[11] Frontiers in metabolic physiology grand challenges

  • Authors: J. Imig
  • Year: 2022
  • Venue: Frontiers in Physiology
  • URL: https://www.semanticscholar.org/paper/19e2780d459288513f034516e0a7d5fa4e12298f
  • DOI: 10.3389/fphys.2022.879617
  • PMID: 36035475
  • PMCID: 9399398
  • Citations: 1
  • Summary: In this chapter seven subsequent studies of the determinants of infectious disease in eight operation rooms were studied.
  • Evidence snippets:
  • Snippet 1 (score: 0.430) > Research in this area will identify novel therapeutic targets for diabetic complications at the levels of transcription and translation, protein expression and activity, and cell and organ levels. Major challenges in diabetes include defining molecular mechanisms and pathways implicated in insulin metabolism, evaluating transcriptomics of high glucose on different cell types, defining the contribution of the innate immune response and NLRP3 inflammasome, understanding metabolic mechanisms that drive beta cell dysfunction, and defining metabolic processes in key insulin-target tissues. > NAFLD is a rapidly growing public health concern that occurs in 25% of the world population and is driven in large part by the obesity and type 2 diabetes epidemic (Caussy et al., 2021;Targher et al., 2021). Intriguingly, NAFLD can be as high as 75% in diabetic patients (Caussy et al., 2021;Targher et al., 2021). Non-alcoholic steatosis (NASH) is a type of NAFLD that is associated with inflammation and hepatocyte lipotoxicity which leads to liver fibrosis and cancer (Caussy et al., 2021;Targher et al., 2021). NASH is expected to become the leading cause for liver transplantation in the next decade (Nephew and Serper, 2021). Mechanisms that contribute to NAFLD and progression to NASH include regulation of de novo lipogenesis by acetyl-CoA carboxylase, regulation of bile acid signaling by farnesoid X receptor (FXR), or oxidative stress induced fibrogenesis and inflammation by apoptosis signal-regulating kinase 1 (ASK1) (Attia et al., 2021;Koo and Han, 2021). Although often associated with obesity and diabetes, understanding pathophysiological mechanisms at the cellular hepatocyte and organ liver levels that result in NAFLD and progression to NASH will be key to developing therapeutics. > Major challenges to the epidemic of metabolic diseases are the focus of several publications in Frontiers in Metabolic Physiology. Studies in mice with type 2 diabetes have revealed metabolites involved in diabetic kidney disease.

[12] Cellular and molecular mechanisms of aspartoacylase and its role in Canavan disease

  • Authors: Martin Grønbæk-Thygesen, R. Hartmann-Petersen
  • Year: 2024
  • Venue: Cell & Bioscience
  • URL: https://www.semanticscholar.org/paper/d2dfbaee9666d4b1f681d466dae63d5a770fd34a
  • DOI: 10.1186/s13578-024-01224-6
  • PMID: 38582917
  • PMCID: 10998430
  • Citations: 7
  • Summary: The importance of high-throughput technologies and computational prediction tools for making genotype–phenotype predictions as they await the results of ongoing trials with gene therapy for Canavan disease is highlighted.
  • Evidence snippets:
  • Snippet 1 (score: 0.424) > Canavan disease is an autosomal recessive and lethal neurological disorder, characterized by the spongy degeneration of the white matter in the brain. The disease is caused by a deficiency of the cytosolic aspartoacylase (ASPA) enzyme, which catalyzes the hydrolysis of N-acetyl-aspartate (NAA), an abundant brain metabolite, into aspartate and acetate. On the physiological level, the mechanism of pathogenicity remains somewhat obscure, with multiple, not mutually exclusive, suggested hypotheses. At the molecular level, recent studies have shown that most disease linked ASPA gene variants lead to a structural destabilization and subsequent proteasomal degradation of the ASPA protein variants, and accordingly Canavan disease should in general be considered a protein misfolding disorder. Here, we comprehensively summarize the molecular and cell biology of ASPA, with a particular focus on disease-linked gene variants and the pathophysiology of Canavan disease. We highlight the importance of high-throughput technologies and computational prediction tools for making genotype–phenotype predictions as we await the results of ongoing trials with gene therapy for Canavan disease.

[13] iPSC‐Derived Liver Organoids as a Tool to Study Medium Chain Acyl‐CoA Dehydrogenase Deficiency

  • Authors: L. A. Kiyuna, José M. Horcas-Nieto, Christoff Odendaal, Miriam Langelaar-Makkinje, A. Gerding et al.
  • Year: 2025
  • Venue: Journal of Inherited Metabolic Disease
  • URL: https://www.semanticscholar.org/paper/547bf305207cfd00da79f778ed7ea7eb255f1018
  • DOI: 10.1002/jimd.70028
  • PMID: 40199742
  • PMCID: 11978564
  • Citations: 2
  • Summary: iPSC‐derived organoids of MCADD patients recapitulated the major biochemical phenotype of the disease, and this patient‐specific hepatic organoid system is a promising platform to study the phenotypic heterogeneity between MCADD patients.
  • Evidence snippets:
  • Snippet 1 (score: 0.423) > Medium chain acyl‐CoA dehydrogenase deficiency (MCADD) is an inherited metabolic disease, characterized by biallelic variants in the ACADM gene. Interestingly, even with the same genotype, patients often present with very heterogeneous symptoms, ranging from fully asymptomatic to life‐threatening hypoketotic hypoglycemia. The mechanisms underlying this heterogeneity remain unclear. Therefore, there is a need for in vitro models of MCADD that recapitulate the clinical phenotype as a tool to study the pathophysiology of the disease. Fibroblasts of control and symptomatic MCADD patients with the c.985A>G (p.K329E) were reprogrammed into induced pluripotent stem cells (iPSCs). iPSCs were then differentiated into hepatic expandable organoids (EHOs), further matured to Mat‐EHOs, and functionally characterized. EHOs and Mat‐EHOs performed typical hepatic metabolic functions, such as albumin and urea production. The organoids metabolized fatty acids, as confirmed by acyl‐carnitine profiling and high‐resolution respirometry. MCAD protein was fully ablated in MCADD organoids, in agreement with the instability of the mutated MCAD protein. MCADD organoids accumulated medium‐chain acyl‐carnitines, with a strongly elevated C8/C10 ratio, characteristic of the biochemical phenotype of the disease. Notably, C2 and C14 acyl‐carnitines were found decreased in MCADD Mat‐EHOs. Finally, MCADD organoids exhibited differential expression of genes involved in ω‐oxidation, mitochondrial β‐oxidation, TCA cycle, and peroxisomal coenzyme A metabolism, particularly upregulation of NUDT7. iPSC‐derived organoids of MCADD patients recapitulated the major biochemical phenotype of the disease. Mat‐EHOs expressed relevant pathways involved in putative compensatory mechanisms, notably CoA metabolism and the TCA cycle. The upregulation of NUDT7 expression may play a role in preventing excessive accumulation of dicarboxylic acids

[14] Investigating the Transition of Pre-Symptomatic to Symptomatic Huntington’s Disease Status Based on Omics Data

  • Authors: Christiana C. Christodoulou, M. Zachariou, Marios Tomazou, E. Karatzas, C. Demetriou et al.
  • Year: 2020
  • Venue: International Journal of Molecular Sciences
  • URL: https://www.semanticscholar.org/paper/04a48e68a0a0ad9eca22aeffdb8c22c7fb41ed86
  • DOI: 10.3390/ijms21197414
  • PMID: 33049985
  • PMCID: 7582902
  • Citations: 26
  • Influential citations: 2
  • Summary: The genes, pathways and metabolites identified for each HD stage can provide a better understanding of the mechanisms that become altered in each disease stage, leading to an improvement in clinical symptoms and hopefully a delay in the age of onset.
  • Evidence snippets:
  • Snippet 1 (score: 0.423) > HD is a monogenetic and incurable disease and at the same time its molecular manifestations remain highly complex and involve multiple cellular processes, genes, and metabolites, which needs to be investigated to understand HD pathology. Systems bioinformatics (SB) allows the integration of different biological omics data to better understand the biological pathways, mechanisms, genes and metabolites involved in HD and lead to possible therapeutic treatments and biomarker discovery. > SB is an interdisciplinary field which combines the research fields of systems biology and bioinformatics. SB allows the integration of biological data across the omics categories such a genomics, transcriptomics, proteomics, metabolomics, lipidomics, epigenomics and several types of omics data [7]. > A major approach in this direction is the generation and construction of biological networks representing each level of omics data and their integration in a layered network that permits the exchange of information between and within the layers. The goal is to reveal synergistic relationships among numerous factors rather than explore each entity individually. This data integration approach results in the construction of highly complex molecular interaction networks. The biological data, obtained through large-scale omics analysis can provide a better understanding into biological mechanisms and pathways and how a dysfunction in these mechanisms and pathways can cause the disease [7]. Furthermore, the emerging importance of biological network-based approaches, allows for potential biological and clinical applications by suggesting an intuitive and trustworthy approach to explore the biological and molecular complexity of a disease of interest [8]. > The metabolome is defined as the complete set of small chemical molecules found within a biological samples (urine, cerebrospinal fluid (CSF), serum, plasma), tissues and cells. Changes and interactions in gene and protein expression and the environment are directly revealed in the metabolome making it more chemically and physically complex than the genome, transcriptome and proteome. Metabolites are affected by the upstream influence of the genome, proteome, environmental and lifestyle factors, as well as medication and underlying diseases [9]. > Metabolomics is an omics category focused in the study of metabolites. Metabolites are defined as small biological and low molecular weight (<1500 Da) compounds, they are the end-products of metabolism [10].

[15] Exome and genome sequencing: a revolution for the discovery and diagnosis of monogenic disorders

  • Authors: H. Stranneheim, A. Wedell
  • Year: 2016
  • Venue: Journal of Internal Medicine
  • URL: https://www.semanticscholar.org/paper/112c148c6b98b6d169cd0b67d258f97d4a225a8d
  • DOI: 10.1111/joim.12399
  • PMID: 26250718
  • Citations: 92
  • Influential citations: 3
  • Summary: Not only can rapid and safe diagnostics of virtually all known single‐gene defects now be established, but novel causes of disease in previously unsolved cases can also be identified, illuminating novel pathways important for normal physiology.
  • Evidence snippets:
  • Snippet 1 (score: 0.422) > Deficiency of 3-hydroxyisobutyryl-CoA hydrolase (HIBCH) is a rare defect in the valine catabolic pathway associated with severe brain damage (Leigh-like disease). Mutations in the HIBCH gene were excluded in patients with a remarkably similar biochemical and clinical phenotype. Exome sequencing instead identified mutations in the ECHS1 gene-encoding short-chain enoyl-CoA hydratase. This mitochondrial enzyme is active immediately upstream of HIBCH in the valine degradation pathway [30]. > A subgroup amongst IEMs is the mitochondrial disorders, resulting from impaired oxidative phosphorylation. These disorders affect at least 1 in 5000 live births [31] and can be caused by mutations in nuclear genes or in mitochondrial DNA (mtDNA). The small, circular mtDNA molecule encodes 13 components of the respiratory chain as well as two ribosomal RNAs (rRNAs) and 22 transfer RNAs (tRNAs) required for the mitochondrial translational machinery. The majority of the subunits of the respiratory chain as well as factors required for maintenance and expression of mtDNA, including replication, transcription and translation, are encoded by nuclear DNA genes (Fig. 2). Mitochondrial function thus depends critically on the coordinated expression of genes from two genomes. Around 100 mostly recessive nuclear genes are currently known to cause mitochondrial disorders, and the number is increasing rapidly due in large part to exome sequencing. > One approach to facilitating the discovery of novel disease genes causing mitochondrial disorders relied on specifically targeting the mitochondrial genome together with all coding exons of the approximately 1000 nuclear genes known to be located inside the mitochondria in patients with biochemical evidence of impaired mitochondrial function [32]. More important, however, is the possibility of directly combining biochemical and genetic investigations. Detailed characterization of mitochondrial respiratory chain function in cells or tissue from affected patients can locate defects such as in the synthesis or assembly of specific enzyme complexes required for oxidative phosphorylation, providing a functional framework to aid the identification and validation of pathogenic variants. For example, when mutations in NDUFB3, encoding a subunit of complex I, were identified in a patient with severe, early lethal mitochondrial disease due to complex I deficiency, these could indeed be considered pathogenic even though mutations in this gene had not previously been reported

[16] New therapeutic targets in rare genetic skeletal diseases

  • Authors: M. Briggs, Peter A. Bell, M. Wright, K. A. Pirog
  • Year: 2015
  • Venue: Expert Opinion on Orphan Drugs
  • URL: https://www.semanticscholar.org/paper/1363107f71ae6d2d60abca471cddf3da5d13644b
  • DOI: 10.1517/21678707.2015.1083853
  • PMID: 26635999
  • PMCID: 4643203
  • Citations: 37
  • Influential citations: 1
  • Summary: An overview of disease mechanisms that are shared amongst groups of different GSDs and potential therapeutic approaches that are under investigation are described to generate critical mass for the identification and validation of novel therapeutic targets and biomarkers.
  • Evidence snippets:
  • Snippet 1 (score: 0.422) > proteins of the cartilage ECM such as type II collagen [50]. However, emerging knowledge suggests that the primary genetic defect may be less important than the cells' response to the expression of the mutant gene product [107]. Moreover, the largely overlooked response of a cell (i.e. chondrocyte) to the abnormal extracellular environment is also important for disease progression as illustrated by several GSDs discussed in this review. > It is important that 'omics'-based approaches and technologies are systematically applied to the study of rare GSDs so that definitive reference profiles and disease signatures are generated for each phenotype. These can then be used in a Systems Biology approach to identify both common and dissimilar pathological signatures and disease mechanisms. This approach is entirely dependent upon relevant in vitro and in vivo models (and also novel 'disease-mechanism phenocopies' [107]) for testing new diagnostic and prognostic tools and for determining the molecular mechanisms that underpin the pathophysiology so that effective therapeutic treatments can be developed and validated. This approach will eventually lead to personalized treatments and care strategies centred on shared disease mechanisms with the use of relevant biomarkers to monitor the efficacy of treatment and disease progression. > It is vital that all relevant stakeholders are involved from the outset in defining the appropriate outcomes of any potential therapeutic regime. The perceptions of a successful therapy can differ widely between the clinical academic community and the relevant patient-support groups and it is vital that there is engagement on all these issues. > In summary, the identification of causative genes and mutations for GSDs over the last 20 years, coupled with the generation and in-depth analysis of a plethora of relevant cell and mouse models, has derived new knowledge on disease mechanisms and suggested potential therapeutic targets. The fast-evolving hypothesis that clinically disparate diseases can share common disease mechanisms is a powerful concept that will generate critical mass for the identification and validation of novel therapeutic targets and biomarkers.

[17] [Retracted] Identification of HIBCH as a Fatty Acid Metabolism‐Related Biomarker in Aortic Valve Calcification Using Bioinformatics

  • Authors: Jun-Yu Chen, Ya-Ru Sun, Tao Xiong, Guan-nan Wang, Qing Chang
  • Year: 2022
  • Venue: Oxidative Medicine and Cellular Longevity
  • URL: https://www.semanticscholar.org/paper/8d3a50a11e93a0e40c20eac1e66ea3b47476e3e1
  • DOI: 10.1155/2022/9558713
  • Citations: 1
  • Summary: 3‐hydroxyisobutyryl‐CoA hydrolase (HIBCH) was a biomarker of fatty acid metabolism‐related genes in AVC and could be applied as a diagnostic marker for AVC.
  • Evidence snippets:
  • Snippet 1 (score: 0.419) > The results showed a significant association between HIBCH and various immune cells. This suggests that HIBCH in AVC tissues might impact the Oxidative Medicine and Cellular Longevity progression of AVC by affecting immune cells. The GSEA results provide additional evidence that HIBCH may act through immune-related pathways. HIBCH (3-hydroxyisobutyryl-CoA hydrolase) is an enzyme that catalyzes the conversion of 3-hydroxyisobutyryl-CoA to 3-hydroxyisobutyric acid [27]. It is a key mitochondrial protein required for valine catabolism [28,29]. The metabolite 3-hydroxyisobutyric acid is transformed further to succinyl coenzyme A which is involved in the metabolism of the tricarboxylic acid (TCA) cycle. A prior research has reported the involvement of HIBCH in hepatic mitochondrial fatty acid oxidation [30]. Various studies have shown that HIBCH is related to colorectal cancer [31], ovarian cancer [32,33], prostate cancer [34], paroxysmal dyskinesia [35], and Leigh syndrome [36][37][38][39]. In addition, a study also showed the association between HIBCH with AVC [40]. > With the advancement in the understanding of AVC, various researches have demonstrated the effect of immune cells in AVC. Previous studies have shown that both antigen-presenting cells (APCs) and macrophages exist in normal and pathologic valves, but the existence of T lymphocytes is characteristic of both aging and pathologic valves [41,42]. This lymphocytic infiltration is accompanied by increased neointima formation and osteogenesis, which is the hallmark and pathological signs of AVC [43]. The abundance of B lymphocytes in the valves is related to increased disease severity. In addition, prior researches showed that the depletion of natural killer T (NKT) cells can lead to improvement or worsening of a variety of fibrotic diseases [44][45][46].

[18] Exome sequencing and metabolomic analysis of a chronic kidney disease and hearing loss patient family revealed RMND1 mutation induced sphingolipid metabolism defects

  • Authors: Nagwa Gaboon, B. Banaganapalli, K. Nasser, M. Razeeth, Mosab S. Alsaedi et al.
  • Year: 2019
  • Venue: Saudi Journal of Biological Sciences
  • URL: https://www.semanticscholar.org/paper/f1f1341fd61e31f39a5129e7c80ff67cd0b6fb0f
  • DOI: 10.1016/j.sjbs.2019.10.001
  • PMID: 31889854
  • PMCID: 6933272
  • Citations: 17
  • Influential citations: 1
  • Summary: Genetic defects in RMND1 gene alters the mitochondrial energy metabolism leading to the accumulation of ceramide, and subsequently promote dysregulated apoptosis and tissue necrosis in kidneys, this study suggests.
  • Evidence snippets:
  • Snippet 1 (score: 0.416) > One of the recently identified nuclear genes involved in mitochondrial respiratory chain deficiencies is RMND1 (Required for Meiotic Nuclear Division protein 1) (Garcia-Diaz et al., 2012;Janer et al., 2012). It has been demonstrated that various novel and common recessive mutations in RMND1 are associated with multiple phenotypes characterized by delayed maturation of vision, developmental delay, dilated cardiomyopathy, deafness and neurological defects (Gupta et al., 2016), renal tubular acidosis type 4 presented as hyponatraemia and hyperkalaemia and cystic/hypoplastic kidneys (Ng et al., 2016). Likewise, complex clinical spectrum of patients with RMND1 mutations is emerging with infantile encephalomyopathy with lactic acidosis (Garcia-Diaz et al., 2012;Casey et al., 2016) to a less severe form of developmental delay, hypotonia, renal disease and congenital sensorineural deafness (Janer et al., 2015). Therefore, molecular screening of RMND1 gene will help identify the inheritance mode of causative genetic mutations in patients with renal and or neurological defects. > MIDs have complex etiologies with underlying cross talk of inter and intra molecular signaling. Hence, metabolomic studies on these patients could provide a better understanding of the interconnectivity between genetic and molecular networks (Davies, 2018). Metabolomic profiling examines the metabolic changes in body fluids driven from cellular processes to understand the onset and pathogenesis of disease phenotype (Abbiss et al., 2019). Metabolomics analyzes metabolites by either targeted or untargeted approaches. The untargeted approach involves hypothesis free surveying of hundreds of thousands of small molecule metabolites for discovering novel mechanisms or pathways, whereas the targeted one refers to measuring predefined sets of metabolites, typically focusing on a few pathways of interest (Kalim and Rhee, 2017). The specific relationship between inherited mutations in mitochondrial proteins and their functional impacts in terms of metabolic defects in chronic kidney disease (CKD) is not yet well characterized.

[19] Diet and Nutrients in Rare Neurological Disorders: Biological, Biochemical, and Pathophysiological Evidence

  • Authors: Marilena Briglia, Fabio Allia, R. Avola, C. Signorini, V. Cardile et al.
  • Year: 2024
  • Venue: Nutrients
  • URL: https://www.semanticscholar.org/paper/7308e8ab8a771741ed66510938d52004f1d64f92
  • DOI: 10.3390/nu16183114
  • PMID: 39339713
  • PMCID: 11435074
  • Citations: 5
  • Influential citations: 1
  • Summary: This work aims to collect the in vitro, in vivo, and clinical evidence on the effects of diet and of nutrient intake on some rare neurological disorders, including some genetic diseases, and rare brain tumors.
  • Evidence snippets:
  • Snippet 1 (score: 0.414) > The relationship between nutritional intervention and rare neurological diseases is an emerging area of research that may help to manage symptoms, slow disease progression, or even impact the underlying mechanisms of certain rare neurological disorders. The complex interactions between diet and neurological health require closer interdisciplinary collaboration between neurologists, dietitians, and researchers. It is crucial to conduct clinical trials to establish evidence-based dietary guidelines tailored to these unique conditions. > The major limits of this study reside in (i) the limited availability of data as accessed by the reduced number of published papers and completed clinical trials; (ii) the wide variety of the disease's pathophysiology; and (iii) the underestimated influence of individual variability due to genetic differences. Specifically, as reported above, the number of published articles about the role of diet/nutrients on rare neurological disorders is very small. Clinical data often derive from case reports or small cohort studies, and large-scale clinical trials are scarce due to the rarity of these disorders and the huge heterogeneity of clinical manifestations. Moreover, even if preclinical studies give us more detailed information about the impact of a specific nutrient on cell function or on disease progression in animal models, they could not reflect the patients' individual genetic differences and their global health status (e.g., integrity of anatomic structure and physiological functions as blood circulation, pressure, constipation, and deglutition). These latter aspects may influence how patients assume, metabolize, and distribute nutrients as has been discussed above in the case of cholesterol supplementation for Pelizaeus-Merzbacher disease. > Moreover, when searching for dietary recommendations for a specific rare disease, a great limit is the heterogeneity of occurring genetic mutations that turn into different phenotypes and clinical manifestations. Briefly, what could work for one patient may not be effective for another one, as enlightened here by reviewing the activity of trihydroxyisoflavone as a GALC-addressed chaperone. > However, despite these limitations, our analysis has, as a strength, the identification of a specific dietary intervention for the management of some symptoms. It is the case of ketogenic diet efficacy in different rare neurological diseases that share epilepsy in clinical manifestation.

[20] HMG-CoA Lyase Deficiency: A Retrospective Study of 62 Saudi Patients

  • Authors: M. Alfadhel, Basma Abadel, Hind Almaghthawi, Muhammad Umair, Z. Rahbeeni et al.
  • Year: 2022
  • Venue: Frontiers in Genetics
  • URL: https://www.semanticscholar.org/paper/080356c04b117156bf7674f3ee445870810ce7d0
  • DOI: 10.3389/fgene.2022.880464
  • PMID: 35646072
  • PMCID: 9136170
  • Citations: 17
  • Influential citations: 1
  • Summary: This is the largest cohort of HMGCLD patients reported from Saudi Arabia, signifying this disorder as a likely life-threatening disease, with a high prevalence in the region, and suggest that diagnosis at an early stage with careful dietary management may avoid metabolic crises.
  • Evidence snippets:
  • Snippet 1 (score: 0.409) > Therefore, the first step in the diagnosis is the MS/MS-based acylcarnitine profiling in dried blood spots/ plasma and the GC/MS-based organic acid analysis in urine. Then, molecular diagnosis using next-generation sequencing should be followed to pinpoint precisely the genetic cause of the disease (Ismail et al., 2019;Alfadhel et al., 2021). Similarly, targeted newborn screening should also be initiated to eradicate this severe disorder (Alfadhel et al., 2019). Similarly, Reimão et al. described late-onset diseases where a 29-year-old man with no prior medical history presented sudden coma, profound hypoglycemia, hyperammonemia, and metabolic acidosis without ketosis (Reimão et al., 2009). A 36-year-old woman with a late onset of an acute episode of hyperproteinorachia (0.73 g/L), hypoglycemia, and generalized seizures has also been reported (Bischof et al., 2004). Patients showing different levels of severity in the phenotypic presentation highlight clinical heterogeneity of the disorder. Still, it is difficult to establish a proper genotype-phenotype correlation in HMGCLD (Grunert et al., 2017;Alfadhel et al., 2017). > The mechanism of neurological pathophysiology in HGMCLD is still poorly understood; however, possible mechanisms include secondary carnitine deficiency, hypoketotic hypoglycemia, and intracellular toxic organic acid accumulation (Puisac et al., 2010). Furthermore, MRI shows a unique combination of T2-weighted diffuse mild signal changes with multiple foci of a more severe signal abnormality (Legault et al., 2015). Studies using rats revealed that the accumulation of the metabolite in HMGCLD results in oxidative stress in the developing rat's striatum that disrupts bioenergetics dynamics, signaling pathways, and ER-mitochondria communication, which might explain the HMGCLD disease pathogenesis (da Rosa et al., 2015).

Notes

  • This provider combines search_papers_by_relevance with snippet_search.
  • No synthesis or second-stage model call is performed.
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Disease Characteristics Research Template
Edison Scientific Literature 25 citations 2026-05-29T19:35:32.633255

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on: 1. Key concepts and definitions with current understanding 2. Recent developments and latest research (prioritize 2023-2024 sources) 3. Current applications and real-world implementations 4. Expert opinions and analysis from authoritative sources 5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available. Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Disease Characteristics Research Template

Target Disease

  • Disease Name: 3-hydroxyisobutyryl-CoA hydrolase deficiency
  • MONDO ID: (if available)
  • Category: Mendelian

Research Objectives

Please provide a comprehensive research report on 3-hydroxyisobutyryl-CoA hydrolase deficiency covering all of the disease characteristics listed below. This report will be used to populate a disease knowledge base entry. Be thorough and cite primary literature (PMID preferred) for all claims.

For each section, suggested databases/resources are listed. These are the first places you should search for information on each topic.


1. Disease Information

Search first: OMIM, Orphanet, ICD-10/ICD-11, MeSH, PubMed

  • What is the disease? Provide a concise overview.
  • What are the key identifiers? (OMIM, Orphanet, ICD-10/ICD-11, MeSH, Mondo)
  • What are the common synonyms and alternative names?
  • Is the information derived from individual patients (e.g., EHR) or aggregated disease-level resources?

2. Etiology

  • Disease Causal Factors: What are the primary causes? (genetic, environmental, infectious, mechanistic)
  • Risk Factors:

    Search first: PubMed, Cochrane Library, UpToDate, clinical guidelines, ClinVar, ClinGen, GWAS Catalog, PheGenI, CTD, CDC, WHO, epidemiological databases

  • Genetic risk factors (causal variants, susceptibility loci, modifier genes)
  • Environmental risk factors (toxins, lifestyle, occupational exposures, age, sex, family history)
  • Protective Factors:

    Search first: PubMed, Cochrane Library, clinical trial databases, GWAS Catalog, gnomAD, WHO, CDC, nutrition databases

  • Genetic protective factors (protective variants, modifier alleles)
  • Environmental protective factors (diet, lifestyle, exposures that reduce risk)
  • Gene-Environment Interactions: How do genetic and environmental factors interact to influence disease?

    Search first: CTD, PubMed, PheGenI, GxE databases

3. Phenotypes

Search first: HPO (Human Phenotype Ontology), OMIM, Orphanet, PubMed, clinicaltrials.gov, MedDRA, SNOMED CT, DECIPHER, LOINC

For each phenotype, provide: - Phenotype type: symptoms, clinical signs, physical manifestations, behavioral changes, or laboratory abnormalities

For symptoms/signs: HPO, OMIM, Orphanet, PubMed For behavioral changes: HPO, DSM, RDoC (Research Domain Criteria), PubMed For laboratory abnormalities: LOINC, SNOMED CT, LabTests Online, PubMed - Phenotype characteristics: Search first: OMIM, Orphanet, HPO, PubMed - Age of symptom onset (neonatal, childhood, adult-onset, late-onset) - Symptom severity (mild, moderate, severe, variable) - Symptom progression (stable, progressive, episodic, fluctuating) - Frequency among affected individuals (percentage or qualitative) - Quality of life impact: Effects on daily functioning and well-being (per-phenotype when possible) Search first: EQ-5D database, SF-36, WHO QOL databases, PubMed - Suggest HPO (Human Phenotype Ontology) terms for each phenotype

4. Genetic/Molecular Information

  • Causal Genes: Gene mutations or chromosomal abnormalities responsible for disease (gene symbols, OMIM IDs)

    Search first: OMIM, ClinVar, HGMD, Ensembl, NCBI Gene

  • Pathogenic Variants:
  • Affected genes (gene symbols, HGNC IDs) > Search first: OMIM, NCBI Gene, Ensembl, HGNC, UniProt, GeneCards
  • Variant classification (pathogenic, likely pathogenic, VUS per ACMG/AMP guidelines) > Search first: ClinVar, ClinGen, ACMG/AMP guidelines, VarSome
  • Variant type/class (missense, frameshift, nonsense, splice-site, structural)
  • Allele frequency in population databases > Search first: gnomAD, 1000 Genomes, ExAC, TOPMed, dbSNP
  • Somatic vs germline origin > Search first: COSMIC (somatic), ClinVar, ICGC, TCGA
  • Functional consequences (loss of function, gain of function, dominant negative)
  • Modifier Genes: Genes that modify disease severity or expression
  • Epigenetic Information: DNA methylation, histone modifications, chromatin changes affecting disease

    Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth

  • Chromosomal Abnormalities: Large-scale genetic changes (aneuploidy, translocations, inversions)

    Search first: DECIPHER, ClinVar, ECARUCA, UCSC Genome Browser

5. Environmental Information

  • Environmental Factors: Non-genetic contributing factors (toxins, radiation, pollution, occupational exposure)

    Search first: CTD (Comparative Toxicogenomics Database), TOXNET, PubMed, EPA databases

  • Lifestyle Factors: Behavioral factors (smoking, diet, exercise, alcohol consumption)

    Search first: CDC databases, WHO, PubMed, NHANES

  • Infectious Agents: If applicable, pathogens causing or triggering disease (bacteria, viruses, fungi, parasites)

    Search first: NCBI Taxonomy, ViPR, BV-BRC, MicrobeDB, GIDEON

6. Mechanism / Pathophysiology

  • Molecular Pathways: Specific signaling cascades or biochemical pathways involved (Wnt, MAPK, mTOR, PI3K-AKT, etc.)

    Search first: KEGG, Reactome, WikiPathways, PathBank, BioCyc

  • Cellular Processes: Cell-level mechanisms (apoptosis, autophagy, cell cycle dysregulation, inflammation, etc.)

    Search first: Gene Ontology (GO), Reactome, KEGG, PubMed

  • Protein Dysfunction: How protein structure or function is altered (misfolding, aggregation, loss of function, gain of function)

    Search first: UniProt, PDB (Protein Data Bank), InterPro, Pfam, AlphaFold

  • Metabolic Changes: Alterations in metabolic processes (energy metabolism, lipid metabolism, amino acid metabolism)

    Search first: KEGG, BioCyc, HMDB (Human Metabolome Database), BRENDA

  • Immune System Involvement: Role of immune response (autoimmunity, immunodeficiency, chronic inflammation)

    Search first: ImmPort, Immunome Database, IEDB, Gene Ontology

  • Tissue Damage Mechanisms: How tissues/ are injured (oxidative stress, ischemia, fibrosis, necrosis)

    Search first: PubMed, Gene Ontology, Reactome

  • Biochemical Abnormalities: Specific molecular defects (enzyme deficiencies, receptor dysfunction, ion channel defects)

    Search first: BRENDA, UniProt, KEGG, OMIM, PubMed

  • Epigenetic Changes: DNA methylation, histone modifications affecting gene expression in disease

    Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth

  • Molecular Profiling (if available):
  • Transcriptomics/gene expression changes > Search first: GEO (Gene Expression Omnibus), ArrayExpress, GTEx, Human Cell Atlas, SRA
  • Proteomics findings > Search first: PRIDE, ProteomeXchange, Human Protein Atlas, STRING, BioGRID
  • Metabolomics signatures > Search first: MetaboLights, Metabolomics Workbench, HMDB, METLIN
  • Lipidomics alterations > Search first: LIPID MAPS, SwissLipids, LipidHome, Metabolomics Workbench
  • Genomic structural features > Search first: UCSC Genome Browser, Ensembl, NCBI, dbVar, DGV
  • Advanced Technologies (if applicable):
  • Single-cell analysis findings (cell-type specific mechanisms, cellular heterogeneity) > Search first: Human Cell Atlas, Single Cell Portal, GEO, CELLxGENE
  • Spatial transcriptomics findings > Search first: GEO, Spatial Research, Vizgen, 10x Genomics data
  • Multi-omics integration results > Search first: TCGA, ICGC, cBioPortal, LinkedOmics, PubMed
  • Functional genomics screens (CRISPR, RNAi) > Search first: DepMap, GenomeRNAi, PubMed, BioGRID ORCS

For each mechanism, describe: - The causal chain from initial trigger to clinical manifestation - Which mechanisms are upstream vs downstream - What cell types and biological processes are involved - Suggest GO terms for biological processes and CL terms for cell types

7. Anatomical Structures Affected

  • Organ Level:
  • Primary organs directly affected
  • Secondary organ involvement (complications, secondary effects)
  • Body systems involved (cardiovascular, nervous, digestive, respiratory, endocrine, etc.)

    Search first: Uberon, FMA (Foundational Model of Anatomy), OMIM, HPO, ICD-11, MeSH, SNOMED CT

  • Tissue and Cell Level:
  • Specific tissue types affected (epithelial, connective, muscle, nervous)
  • Specific cell populations targeted (with Cell Ontology terms)

    Search first: Uberon, Human Protein Atlas, Cell Ontology, Human Cell Atlas, CellMarker, PanglaoDB

  • Subcellular Level:
  • Cellular compartments involved (mitochondria, nucleus, ER, lysosomes) (with GO Cellular Component terms)

    Search first: Gene Ontology (Cellular Component), UniProt, Human Protein Atlas

  • Localization:
  • Specific anatomical sites (with UBERON terms) > Search first: FMA, Uberon, NeuroNames (for brain), SNOMED CT
  • Lateralization (unilateral, bilateral, asymmetric) > Search first: HPO, clinical literature, imaging databases

8. Temporal Development

  • Onset:
  • Typical age of onset (congenital, pediatric, adult, geriatric)
  • Onset pattern (acute, subacute, chronic, insidious)

    Search first: OMIM, Orphanet, HPO, PubMed

  • Progression:
  • Disease stages (early, intermediate, advanced, end-stage) > Search first: Cancer Staging Manual (AJCC), WHO classifications, PubMed
  • Progression rate (rapid, slow, variable)
  • Disease course pattern (episodic, relapsing-remitting, progressive, stable)
  • Disease duration (self-limited, chronic lifelong)

    Search first: Disease registries, longitudinal cohort databases, natural history studies, PubMed, Orphanet, OMIM

  • Patterns:
  • Remission patterns (spontaneous, treatment-induced) > Search first: Clinical trial databases, disease registries, PubMed
  • Critical periods (time windows of vulnerability or opportunity for intervention) > Search first: PubMed, developmental biology databases, clinical guidelines

9. Inheritance and Population

  • Epidemiology:
  • Prevalence (cases per 100,000 at given time)
  • Incidence (new cases per 100,000 per year)

    Search first: Orphanet, CDC, WHO, GBD (Global Burden of Disease), national registries, SEER, disease registries

  • For Genetic Etiology:
  • Inheritance pattern (AD, AR, X-linked, mitochondrial, multifactorial, polygenic) > Search first: OMIM, Orphanet, ClinVar, GTR (Genetic Testing Registry)
  • Penetrance (complete, incomplete, age-dependent) > Search first: ClinVar, OMIM, PubMed, ClinGen
  • Expressivity (variable, consistent) > Search first: OMIM, ClinVar, PubMed
  • Genetic anticipation (increasing severity in successive generations) > Search first: OMIM, PubMed (especially for repeat expansion disorders)
  • Germline mosaicism > Search first: ClinVar, OMIM, genetic counseling literature, PubMed
  • Founder effects (population-specific mutations) > Search first: gnomAD, population genetics databases, PubMed
  • Consanguinity role > Search first: OMIM, population studies, genetic counseling resources
  • Carrier frequency > Search first: gnomAD, carrier screening databases, GeneReviews, GTR
  • Population Demographics:
  • Affected populations (ethnic or demographic groups with higher prevalence) > Search first: gnomAD, 1000 Genomes, PAGE Study, PubMed, population registries
  • Geographic distribution (endemic areas, regional variation) > Search first: WHO, CDC, GBD, Orphanet, geographic epidemiology databases
  • Geographic distribution of specific variants
  • Sex ratio (male:female) > Search first: Disease registries, OMIM, PubMed, epidemiological databases
  • Age distribution of affected individuals > Search first: CDC, disease registries, SEER, Orphanet

10. Diagnostics

  • Clinical Tests:
  • Laboratory tests (blood, urine, tissue chemistry, specific enzyme assays) > Search first: LOINC, LabTests Online, PubMed
  • Biomarkers (proteins, metabolites, genetic markers, circulating biomarkers) > Search first: FDA Biomarker List, BEST (Biomarkers, EndpointS, and other Tools), PubMed
  • Imaging studies (X-ray, CT, MRI, PET, ultrasound) > Search first: RadLex, DICOM, Radiopaedia, imaging databases
  • Functional tests (pulmonary function, cardiac stress tests) > Search first: LOINC, clinical guidelines, PubMed
  • Electrophysiology (EEG, EMG, ECG, nerve conduction studies) > Search first: LOINC, clinical neurophysiology databases, PubMed
  • Biopsy findings (histopathology, immunohistochemistry) > Search first: SNOMED CT, College of American Pathologists resources, PubMed
  • Pathology findings (microscopic examination) > Search first: SNOMED CT, Digital Pathology databases, PubMed
  • Genetic Testing:

    Search first: GTR (Genetic Testing Registry), GeneReviews, ClinGen

  • Overview of recommended genetic testing approach
  • Whole genome sequencing (WGS) utility > Search first: GTR, ClinVar, GEL (Genomics England), gnomAD
  • Whole exome sequencing (WES) utility > Search first: GTR, ClinVar, OMIM, GeneMatcher
  • Gene panels (which panels, which genes) > Search first: GTR, ClinVar, laboratory-specific databases
  • Single gene testing > Search first: GTR, ClinVar, OMIM, GeneReviews
  • Chromosomal microarray (CMA) > Search first: DECIPHER, ClinVar, dbVar, ECARUCA
  • Karyotyping > Search first: Chromosome Abnormality Database, ClinVar, cytogenetics resources
  • FISH > Search first: ClinVar, cytogenetics databases, PubMed
  • Mitochondrial DNA testing > Search first: MITOMAP, MSeqDR, ClinVar, GTR
  • Repeat expansion testing > Search first: GTR, ClinVar, repeat expansion databases, PubMed
  • Omics-Based Diagnostics (if applicable):
  • RNA sequencing / transcriptomics > Search first: GEO, ArrayExpress, GTEx, RNA-seq databases
  • Proteomics > Search first: PRIDE, ProteomeXchange, FDA Biomarker database
  • Metabolomics > Search first: MetaboLights, Metabolomics Workbench, HMDB
  • Epigenomics > Search first: GEO, ENCODE, Roadmap Epigenomics, MethBase
  • Liquid biopsy > Search first: COSMIC, ClinVar, liquid biopsy databases, PubMed
  • Clinical Criteria:
  • Standardized diagnostic criteria (DSM, ICD, society guidelines) > Search first: DSM-5, ICD-11, clinical society guidelines, UpToDate
  • Differential diagnosis (other conditions to rule out, with distinguishing features) > Search first: DynaMed, UpToDate, clinical decision support systems
  • Screening:
  • Screening methods for asymptomatic individuals (newborn screening, carrier screening, cascade screening) > Search first: ACMG recommendations, CDC newborn screening, GTR

11. Outcome/Prognosis

  • Survival and Mortality:
  • Survival rate (5-year, 10-year, overall) > Search first: SEER, cancer registries, disease-specific registries, PubMed
  • Life expectancy (with and without treatment if applicable) > Search first: Orphanet, disease registries, actuarial databases, PubMed
  • Mortality rate > Search first: CDC, WHO, GBD, national mortality databases
  • Disease-specific mortality (deaths directly attributable to disease) > Search first: Disease registries, CDC Wonder, GBD, PubMed
  • Morbidity and Function:
  • Morbidity (disease-related disability and health impacts) > Search first: GBD, WHO, disability databases, PubMed
  • Disability outcomes (long-term functional impairments) > Search first: ICF (International Classification of Functioning), disability registries
  • Quality of life measures (EQ-5D, SF-36, PROMIS, disease-specific tools) > Search first: EQ-5D database, SF-36, PROMIS, PubMed
  • Disease Course:
  • Complications (secondary problems: infections, organ failure, etc.) > Search first: ICD codes, disease registries, clinical databases, PubMed
  • Recovery potential (likelihood and extent of recovery, with vs without treatment) > Search first: Natural history studies, rehabilitation databases, PubMed
  • Prediction:
  • Prognostic factors (age, disease severity, biomarkers, treatment response) > Search first: Prognostic models databases, clinical calculators, PubMed
  • Prognostic biomarkers (molecular markers predicting disease course) > Search first: FDA Biomarker database, PubMed, cancer prognostic databases

12. Treatment

  • Pharmacotherapy:
  • Pharmacological treatments (drug names, drug classes, mechanisms of action) > Search first: DrugBank, RxNorm, ATC classification, DailyMed, FDA databases
  • Pharmacogenomics (how genetic variants affect drug metabolism, efficacy, toxicity) > Search first: PharmGKB, CPIC (Clinical Pharmacogenetics), FDA Table of PGx Biomarkers
  • Advanced Therapeutics:
  • Gene therapy (viral vectors, CRISPR, gene replacement, gene editing) > Search first: ClinicalTrials.gov, FDA gene therapy database, ASGCT resources
  • Cell therapy (stem cell transplant, CAR-T, cellular therapeutics) > Search first: ClinicalTrials.gov, FDA cell therapy database, FACT standards
  • RNA-based therapies (ASOs, siRNA, mRNA therapies) > Search first: ClinicalTrials.gov, FDA approvals, PubMed
  • Targeted therapies (treatments directed at specific molecular targets) > Search first: My Cancer Genome, OncoKB, ClinicalTrials.gov, FDA approvals
  • Immunotherapies (checkpoint inhibitors, monoclonal antibodies) > Search first: Cancer Immunotherapy Database, FDA approvals, ClinicalTrials.gov
  • Surgical and Interventional:
  • Surgical interventions (types of surgery, timing, outcomes) > Search first: CPT codes, surgical registries, clinical guidelines, PubMed
  • Supportive and Rehabilitative:
  • Supportive care (symptom management, pain control, nutrition) > Search first: Clinical guidelines, Cochrane Library, PubMed
  • Rehabilitation (physical therapy, occupational therapy, speech therapy) > Search first: Rehabilitation medicine databases, clinical guidelines, PubMed
  • Experimental:
  • Experimental treatments in clinical trials (with NCT identifiers if available) > Search first: ClinicalTrials.gov, EU Clinical Trials Register, WHO ICTRP
  • Treatment Outcomes:
  • Treatment response rates > Search first: Clinical trial databases, FDA reviews, systematic reviews, PubMed
  • Side effects and adverse events > Search first: FDA Adverse Event Reporting System (FAERS), MedWatch, PubMed
  • Treatment Strategy:
  • Treatment algorithms (clinical pathways, decision trees) > Search first: Clinical practice guidelines, NCCN Guidelines, UpToDate
  • Combination therapies > Search first: ClinicalTrials.gov, treatment guidelines, PubMed
  • Personalized medicine approaches (genotype-guided treatment) > Search first: My Cancer Genome, CIViC, PharmGKB, precision medicine databases

For each treatment, suggest MAXO (Medical Action Ontology) terms where applicable.

13. Prevention

  • Prevention Levels:
  • Primary prevention (preventing disease occurrence: vaccination, risk factor modification) > Search first: CDC, WHO, USPSTF recommendations, Cochrane Library
  • Secondary prevention (early detection and treatment: screening programs, early intervention) > Search first: USPSTF, CDC screening guidelines, WHO
  • Tertiary prevention (preventing complications in those with disease) > Search first: Clinical guidelines, disease management protocols, PubMed
  • Immunization: Vaccine strategies (if applicable)

    Search first: CDC vaccine schedules, WHO immunization, FDA vaccine database

  • Screening and Early Detection:
  • Screening programs (population-based: newborn screening, cancer screening) > Search first: CDC screening programs, USPSTF, cancer screening databases
  • Genetic screening (carrier screening, preimplantation genetic diagnosis, prenatal testing) > Search first: ACMG recommendations, ACOG guidelines, GTR
  • Risk stratification (identifying high-risk individuals for targeted prevention) > Search first: Risk prediction models, clinical calculators, PubMed
  • Behavioral Interventions: Lifestyle modifications to reduce risk

    Search first: CDC, WHO, behavioral intervention databases, Cochrane Library

  • Counseling: Genetic counseling (risk assessment, family planning guidance)

    Search first: NSGC resources, ACMG guidelines, GeneReviews

  • Public Health:
  • Public health interventions (sanitation, vector control, health education) > Search first: CDC, WHO, public health databases, PubMed
  • Environmental interventions (reducing environmental risk factors) > Search first: EPA databases, WHO environmental health, PubMed
  • Prophylaxis: Preventive medications or procedures

    Search first: Clinical guidelines, FDA approvals, PubMed

14. Other Species / Natural Disease

  • Taxonomy: Species affected (with NCBI Taxon identifiers)

    Search first: NCBI Taxonomy

  • Breed: Specific breeds affected (with VBO identifiers if applicable)

    Search first: VBO (Vertebrate Breed Ontology)

  • Gene: Orthologous genes in other species (with NCBI Gene IDs)

    Search first: NCBI Gene

  • Natural Disease:
  • Naturally occurring disease in other species (companion animals, wildlife) > Search first: OMIA (Online Mendelian Inheritance in Animals), VetCompass, PubMed
  • Veterinary relevance and importance in animal health > Search first: OMIA, veterinary databases, PubMed
  • Comparative Biology:
  • Comparative pathology (similarities and differences across species) > Search first: OMIA, comparative pathology databases, PubMed
  • Evolutionary conservation of disease mechanisms > Search first: HomoloGene, OrthoMCL, Alliance of Genome Resources
  • Transmission (if applicable):
  • Zoonotic potential > Search first: CDC zoonotic diseases, WHO zoonoses, GIDEON
  • Cross-species susceptibility > Search first: NCBI Taxonomy, veterinary databases, PubMed

15. Model Organisms

  • Model Types:
  • Model organism type (mammalian, invertebrate, cellular, in vitro) > Search first: Alliance of Genome Resources, model organism databases
  • Specific model systems (mouse, rat, zebrafish, Drosophila, C. elegans, yeast, cell lines, organoids, iPSCs) > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, SGD, ATCC, Cellosaurus
  • Induced models (drug treatment, surgical intervention, environmental manipulation) > Search first: MGI, model organism databases, PubMed
  • Genetic Models:
  • Types available (knockout, knock-in, transgenic, conditional, humanized) > Search first: MGI, IMPC, KOMP, EuMMCR, IMSR
  • Model Characteristics:
  • Phenotype recapitulation (how well model reproduces human disease features) > Search first: Model organism databases, comparative studies, PubMed
  • Model limitations (aspects of human disease not captured) > Search first: Model organism databases, PubMed, review articles
  • Applications:
  • Research applications (what aspects of disease can be studied) > Search first: Model organism databases, PubMed
  • Resources:
  • Model databases > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, IMSR, EMMA, MMRRC

Citation Requirements

  • Cite primary literature (PMID preferred) for all mechanistic and clinical claims
  • Prioritize recent reviews and landmark papers
  • Include direct quotes from abstracts where possible to support key statements
  • Distinguish evidence source types: human clinical, model organism, in vitro, computational

Output Format

Structure your response as a comprehensive narrative organized by the sections above. For each section, provide: - Factual content with specific details (numbers, percentages, gene names, variant nomenclature) - Ontology term suggestions (HPO, GO, CL, UBERON, CHEBI, MAXO, MONDO) where applicable - Evidence citations with PMIDs - Direct quotes from abstracts to support key claims - Clear indication when information is not available or not applicable for this disease

This report will be used to populate a disease knowledge base entry with: - Pathophysiology descriptions with causal chains - Gene/protein annotations (HGNC, GO terms) - Phenotype associations (HP terms) with frequencies - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Treatment annotations (MAXO terms) - Evidence items with PMIDs and exact abstract quotes - Epidemiology, prognosis, diagnostic, and prevention information - Animal model descriptions with phenotype recapitulation details

Comprehensive Research Report: 3-hydroxyisobutyryl‑CoA hydrolase deficiency (HIBCH deficiency)

Executive summary

3-hydroxyisobutyryl‑CoA hydrolase deficiency (HIBCH deficiency; HIBCHD) is an ultra-rare autosomal recessive inborn error of mitochondrial valine catabolism caused by biallelic pathogenic variants in HIBCH, typically presenting in infancy with developmental delay/regression and Leigh/Leigh-like neuroimaging (basal ganglia lesions, often globus pallidus) and characteristic metabolite abnormalities such as C4‑OH (hydroxy‑C4) acylcarnitine and valine-pathway urinary metabolites. It is frequently evaluated under the Leigh syndrome spectrum diagnostic framework, where parallel biochemical testing (acylcarnitines + urinary organic acids) alongside NGS/WES is emphasized to accelerate identification of potentially treatable causes. (stiles2015successfuldiagnosisof pages 1-3, wang2021cinicalmetabolicand pages 1-2, marti‐sanchez2021delineatingtheneurological pages 7-8, baldo2024acomprehensiveapproach pages 2-4)

1. Disease information

1.1 What is the disease?

HIBCH deficiency is an inborn error of metabolism due to impaired function of 3-hydroxyisobutyryl‑CoA hydrolase, a mitochondrial enzyme in the valine degradation pathway, leading to a Leigh/Leigh-like neurodegenerative phenotype with episodic metabolic decompensation in many patients. (stiles2015successfuldiagnosisof pages 1-3, jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, wang2021cinicalmetabolicand pages 1-2)

1.2 Key identifiers and database mappings

  • OMIM (disease): 250620 (stiles2015successfuldiagnosisof pages 1-3, jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 1-2, alayed2020metabolicacidosisand pages 2-3)
  • OMIM (gene): HIBCH (gene OMIM 610690) as reported in a 2024 Bahrain cohort paper (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3)
  • MONDO / Orphanet / MeSH / ICD-10/ICD-11: Not identified in the retrieved full-text evidence for this run; these should be added by querying MONDO/Orphanet/MeSH/ICD resources directly in a subsequent curation step. (evidence gap)

1.3 Synonyms / alternative names

  • “HIBCH deficiency”, “HIBCHD”, “3‑hydroxyisobutyryl‑CoA hydrolase deficiency”, and “Leigh/Leigh-like syndrome due to HIBCH variants” are used across the clinical genetics literature. (stiles2015successfuldiagnosisof pages 1-3, wang2021cinicalmetabolicand pages 1-2, taura2023leighlikesyndromewith pages 1-2)

1.4 Evidence sources: individual vs aggregated

The current evidence base is largely derived from case reports and small cohorts, including retrospective clinic cohorts and multi-center natural history-style aggregations. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, wang2021cinicalmetabolicand pages 1-2, marti‐sanchez2021delineatingtheneurological pages 3-5)

2. Etiology

2.1 Disease causal factors

  • Primary cause: biallelic (autosomal recessive) pathogenic variants in HIBCH, disrupting mitochondrial valine catabolism. (stiles2015successfuldiagnosisof pages 1-3, alayed2020metabolicacidosisand pages 2-3)
  • Mechanistic causal link: disruption of the valine pathway leads to accumulation of valine-derived intermediates (including reactive species discussed in the literature), contributing to secondary mitochondrial dysfunction/Leigh-like presentations. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, stiles2015successfuldiagnosisof pages 6-8)

2.2 Risk factors

  • Genetic risk factor: being homozygous/compound heterozygous for pathogenic HIBCH variants; consanguinity is present in some pedigrees and supports autosomal recessive inheritance in affected families. (stiles2015successfuldiagnosisof pages 3-5, kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 3-3)
  • Environmental/triggering factors (precipitants): intercurrent infection/illness and metabolic stress can precipitate encephalopathy/regression in many patients with valine-pathway defects, including HIBCH deficiency. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 4-6, taura2023leighlikesyndromewith pages 1-2)

2.3 Protective factors

No validated genetic or environmental protective factors were identified in the retrieved evidence for HIBCH deficiency. (evidence gap)

2.4 Gene–environment interactions

Evidence is largely descriptive: infections and increased metabolic demands appear to trigger decompensation, but formal gene–environment interaction studies were not identified. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 4-6, taura2023leighlikesyndromewith pages 1-2)

3. Phenotypes (with HPO suggestions)

3.1 Core neurologic phenotype

Commonly reported manifestations include developmental delay/regression, hypotonia, encephalopathy, feeding difficulties, and movement disorders (dystonia/spasticity/ataxia), with seizures and ocular abnormalities in some patients. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, wang2021cinicalmetabolicand pages 1-2, marti‐sanchez2021delineatingtheneurological pages 7-8)

HPO term suggestions (non-exhaustive): - Developmental delay HP:0001263 - Developmental regression HP:0002376 - Hypotonia HP:0001252 - Encephalopathy HP:0001298 - Dystonia HP:0001332 - Spasticity HP:0001257 - Ataxia HP:0001251 - Seizure HP:0001250 - Feeding difficulties HP:0011968 - Optic atrophy HP:0000648 - Nystagmus HP:0000639

3.2 Age of onset and course

  • Onset is typically in infancy/early childhood; one cohort reports onset “from as early as 6 weeks to 6 months” (jishi2024characterizationof3hydroxyisobutyrylcoa pages 4-6), while another case-series reported median onset 13 months (8–18 months) (wang2021cinicalmetabolicand pages 1-2).
  • Course is often progressive and can include episodic worsening with acute encephalopathy. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 4-6, marti‐sanchez2021delineatingtheneurological pages 7-8)

3.3 Neuroimaging phenotype

  • Leigh/Leigh-like basal ganglia involvement is typical; HIBCH deficiency can show “Bilateral globus pallidus T2-WI hyperintensities” as a distinguishing neuroradiologic pattern in comparative series. (marti‐sanchez2021delineatingtheneurological pages 7-8)
  • Longitudinal imaging can show additional features, including progressive cerebellar atrophy in some cases, expanding the known phenotype. (taura2023leighlikesyndromewith pages 1-2)

HPO suggestions: - Abnormality of the basal ganglia HP:0002134 - Abnormal brain MRI signal HP:0012448 - Cerebellar atrophy HP:0001272

3.4 Laboratory abnormalities

Key biochemical findings used clinically include elevated C4‑OH acylcarnitine and urine valine-pathway metabolites (see Diagnostics). (wang2021cinicalmetabolicand pages 1-2, kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 3-3)

3.5 Quality of life

Formal QoL instruments were not identified in the retrieved evidence, but functional outcomes can be severe (persistent developmental delay; loss of ambulation in severe cases), implying substantial QoL impact. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 4-6, taura2023leighlikesyndromewith pages 2-3)

4. Genetic / molecular information

4.1 Causal gene and function

HIBCH catalyzes a step in valine catabolism; in a comparative natural history study, the authors state: “HIBCH catalyses the fifth step of valine catabolism” and note biochemical accumulation of 3-hydroxyisobutyrylcarnitine in HIBCH deficiency. (marti‐sanchez2021delineatingtheneurological pages 3-5, marti‐sanchez2021delineatingtheneurological pages 7-8)

4.2 Pathogenic variant spectrum (examples from cohorts)

  • A 2024 Bahrain cohort reported a novel homozygous variant c.860A>G (p.Asp287Gly) in all eight patients in that cohort. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, jishi2024characterizationof3hydroxyisobutyrylcoa pages 4-6)
  • A 2021 case-series identified six novel variants (including splice and truncating) among eight patients. (wang2021cinicalmetabolicand pages 1-2)
  • A 2015 sibling pair study reported a novel homozygous variant c.196C>T (p.Arg66Trp) and demonstrated enzyme deficiency in fibroblasts. (stiles2015successfuldiagnosisof pages 1-3, stiles2015successfuldiagnosisof pages 3-5)
  • A 2023 case report described two novel variants c.782T>C (p.Leu261Pro) and c.1012-1G>A (compound heterozygous), with long-term MRI follow-up showing progressive cerebellar atrophy. (taura2023leighlikesyndromewith pages 1-2)

Variant class patterns (from cited case series): missense, truncating, and splice-site variants are all represented. (wang2021cinicalmetabolicand pages 1-2, taura2023leighlikesyndromewith pages 1-2)

4.3 Genotype–phenotype correlations (evidence-supported)

A multi-center aggregation reported survival differences suggesting genotype–outcome correlation: - Within HIBCH deficiency, homozygous variants inside/near the catalytic region were associated with worse survival than surface variants (log-rank P = 0.004). (marti‐sanchez2021delineatingtheneurological pages 3-5)

4.4 Modifier genes / epigenetics / chromosomal abnormalities

No modifier genes, epigenetic signatures, or recurrent chromosomal abnormalities were identified in the retrieved evidence. (evidence gap)

5. Environmental information

No specific toxins, lifestyle factors, or infectious agents were identified as causal; however, febrile illness/infection can act as a trigger for acute decompensation. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 4-6, taura2023leighlikesyndromewith pages 1-2)

6. Mechanism / pathophysiology

6.1 Current mechanistic understanding

The working model is that loss of HIBCH activity perturbs valine degradation, with accumulation of upstream metabolites and reactive intermediates, contributing to mitochondrial dysfunction and Leigh/Leigh-like neurodegeneration. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, stiles2015successfuldiagnosisof pages 6-8)

A comparative clinical series emphasizes that HIBCH deficiency’s main biochemical hallmark is “Elevated plasma levels of 3-hydroxyisobutyryl carnitine” (marti‐sanchez2021delineatingtheneurological pages 7-8), and a diagnostic review for Leigh syndrome spectrum notes that in HIBCH deficiency acylcarnitine profiles may show “high levels of 3-hydroxyisobutyryl carnitine.” (baldo2024acomprehensiveapproach pages 2-4)

6.2 Causal chain (clinically oriented)

  1. Biallelic HIBCH variants → reduced HIBCH activity in mitochondria (stiles2015successfuldiagnosisof pages 1-3, stiles2015successfuldiagnosisof pages 3-5)
  2. Impaired valine catabolism → accumulation of valine-pathway metabolites (C4‑OH acylcarnitine; urine organic acids and cysteine/cysteamine conjugates) (wang2021cinicalmetabolicand pages 1-2, kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 3-3)
  3. Secondary mitochondrial dysfunction / energy failure in vulnerable tissues → Leigh/Leigh-like basal ganglia injury (stiles2015successfuldiagnosisof pages 1-3, marti‐sanchez2021delineatingtheneurological pages 7-8)
  4. Clinical manifestations: neurodevelopmental regression, encephalopathy, movement disorders, seizures, feeding difficulties; potentially progressive neurodegeneration (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, marti‐sanchez2021delineatingtheneurological pages 7-8)

6.3 Pathways / ontology mapping suggestions

  • GO biological process (suggestions): valine catabolic process; branched-chain amino acid catabolic process; mitochondrial metabolic process.
  • GO cellular component (suggestions): mitochondrion / mitochondrial matrix.
  • Cell Ontology (CL) suggestions for susceptible cell types: neurons (CL:0000540), astrocytes (CL:0000127), oligodendrocytes (CL:0000128), microglia (CL:0000129) (suggested because disease is primarily neurodegenerative with basal ganglia/cerebellar involvement).

(These ontology suggestions are provided for knowledge base structuring; the specific GO/CL identifiers were not enumerated in the retrieved full-text evidence.)

6.4 Molecular profiling / multi-omics

No transcriptomic/proteomic/metabolomic multi-omics studies specific to HIBCH deficiency were identified in the retrieved evidence set for this run beyond targeted metabolite profiling used diagnostically. (wang2021cinicalmetabolicand pages 1-2)

7. Anatomical structures affected

7.1 Organ-level involvement

The central nervous system is the primary affected system, with imaging lesions in the basal ganglia and sometimes cerebellar atrophy. (marti‐sanchez2021delineatingtheneurological pages 7-8, taura2023leighlikesyndromewith pages 1-2)

UBERON suggestions: - Basal ganglion UBERON:0002420 (suggested) - Globus pallidus UBERON:0001885 (suggested) - Cerebellum UBERON:0002037 (suggested)

7.2 Subcellular localization

Function is mitochondrial; the disease is framed in mitochondrial metabolism and mitochondrial disease diagnostics. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, baldo2024acomprehensiveapproach pages 2-4)

8. Temporal development

  • Typical onset: infancy/early childhood, sometimes within the first months of life. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 4-6, wang2021cinicalmetabolicand pages 1-2)
  • Course patterns: progressive neurodegeneration and/or episodic decompensation; some patients show chronic phases after an acute encephalopathic event. (taura2023leighlikesyndromewith pages 1-2)

9. Inheritance and population

9.1 Inheritance

Autosomal recessive inheritance is supported by multiple pedigrees and case series (biallelic variants; heterozygous parents). (stiles2015successfuldiagnosisof pages 3-5, kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 3-3)

9.2 Epidemiology / frequency estimates

  • A 2024 Bahrain cohort cites OMIM-based estimates: “1 in 127,939 in East Asians” and “1 in 551,545 in Europeans.” (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3)
  • Earlier series also cite incidence on the order of ~1 in 130,000 and suggest underdiagnosis. (stiles2015successfuldiagnosisof pages 1-3, wang2021cinicalmetabolicand pages 1-2)

9.3 Founder effects / population-specific variants

A Bahrain cohort reported a shared homozygous variant in all eight patients (consistent with a local recurrent variant), but also notes no broadly “confirmed founder mutation” across populations. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 4-6)

Carrier frequency estimates from population databases were referenced in the 2015 study’s incidence modeling approach, but detailed per-population carrier frequencies were not present in the retrieved excerpts. (stiles2015successfuldiagnosisof pages 3-5)

10. Diagnostics

10.1 Clinical suspicion

HIBCH deficiency should be considered in infants/children with Leigh/Leigh-like presentation (basal ganglia lesions) and compatible metabolic findings, particularly when valine-pathway metabolites are present. (stiles2015successfuldiagnosisof pages 1-3, kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 1-2)

10.2 Biochemical testing (key real-world implementation)

Common diagnostic markers: - C4‑OH (hydroxy‑C4) acylcarnitine in dried blood spots or plasma; one series reported hydroxy‑C4 elevations on newborn screening cards, supporting NBS detectability when hydroxy‑C4 is measured. (stiles2015successfuldiagnosisof pages 5-6) - Urine metabolites used for screening/confirmation include S-(2-carboxypropyl) cysteine and S-(2-carboxypropyl) cysteamine and their carnitine esters (tandem MS), plus other valine-pathway organic acids. (kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 3-3) - In a longitudinal case-series, urinary 2,3-dihydroxy-2-methylbutyrate was elevated in 6/7 and S-(2-carboxypropyl) cysteamine in 3/3, and dried blood spot C4‑OH elevation occurred in 5/7. (wang2021cinicalmetabolicand pages 1-2)

Important limitation: hydroxy‑C4 can be normal in milder phenotypes; thus reliance on a single marker may miss cases. (kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 1-2)

10.3 Genetic testing

NGS-based testing (gene panels, WES, WGS) is a primary route to diagnosis in modern practice; several reports demonstrate WES/WGS leading to diagnosis, including in Leigh-like presentations with variable/negative metabolic screens. (stiles2015successfuldiagnosisof pages 1-3, taura2023leighlikesyndromewith pages 1-2)

10.4 Enzymatic confirmation

Measurement of HIBCH activity in patient fibroblasts/tissues can confirm diagnosis but may not be widely available in routine clinical settings. (stiles2015successfuldiagnosisof pages 1-3, stiles2015successfuldiagnosisof pages 5-6)

10.5 Leigh syndrome spectrum diagnostic frameworks (2023–2024 development)

A 2024 diagnostic framework for Leigh syndrome spectrum recommends parallel biochemical testing and states: “basic metabolic studies are mandatory for all patients, including an L/P ratio, plasma amino acids and acylcarnitine profiles, and urinary organic acids” and that their approach “characterized 80% of our cohort and promoted specific intervention in 10% of confirmed cases.” (baldo2024acomprehensiveapproach pages 2-4, baldo2024acomprehensiveapproach pages 1-2)

10.6 Newborn screening status

  • Retrospective analysis of newborn screening cards in an affected sibling pair showed elevated hydroxy‑C4 and suggested that “this disorder could be screened for by NBS programs” when hydroxy‑C4 is included/assessed. (stiles2015successfuldiagnosisof pages 1-3, stiles2015successfuldiagnosisof pages 5-6)
  • No evidence was retrieved in this run that HIBCH deficiency is universally included in national newborn screening panels; implementation appears program-dependent. (evidence gap)

10.7 Differential diagnosis (examples)

Valine-pathway and related mitochondrial/Leigh-like conditions (e.g., ECHS1/SCEH deficiency) are prominent differentials; comparative neuroradiology and metabolite patterns (e.g., predominance of globus pallidus involvement; 3-hydroxyisobutyrylcarnitine) can help differentiate. (marti‐sanchez2021delineatingtheneurological pages 7-8, marti‐sanchez2021delineatingtheneurological pages 11-13)

11. Outcomes / prognosis

  • Outcomes vary but can be severe. In the Bahrain cohort, despite interventions, many patients had severe persistent developmental delay and some died due to complications (including sepsis). (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3)
  • Comparative survival analysis across aggregated cohorts found longer survival in HIBCH compared with ECHS1/SCEH deficiency (Breslow test P = 0.036). (marti‐sanchez2021delineatingtheneurological pages 3-5)
  • Earlier onset was associated with poorer prognosis in the Bahrain cohort. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 4-6)

12. Treatment

12.1 Current standard of care (no disease-specific curative therapy)

Management is largely supportive and empiric metabolic therapy: - Dietary management: low-valine / low-protein dietary strategies are commonly suggested/used. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 3-3) - Supplements/adjuncts: carnitine and N-acetylcysteine are commonly mentioned; “mitochondrial cocktail” approaches are described in Leigh-like care contexts. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 3-3) - Acute decompensation care: supportive management (e.g., IV fluids, correction of acidosis, high-glucose support) is described in severe presentations. (kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 3-3)

Evidence for benefit is limited and mainly observational: - In an 8-patient longitudinal case-series, five patients “responded positively to treatment with a significant decrease in NPMDS scores” after drug and dietary treatment. (wang2021cinicalmetabolicand pages 1-2) - In a comparative cohort, only one patient showed “a mild improvement in lower limb dystonia while receiving valine restricted formula,” and most had no clear neurologic improvement. (marti‐sanchez2021delineatingtheneurological pages 7-8)

12.2 MAXO suggestions (treatment action ontology)

  • Dietary amino acid restriction / valine restriction (MAXO term suggestion)
  • Carnitine supplementation (MAXO term suggestion)
  • N-acetylcysteine therapy (MAXO term suggestion)
  • Supportive critical care for metabolic decompensation (MAXO term suggestion)

12.3 Clinical trials

No interventional clinical trials were identified in the tool-run state for HIBCH deficiency. (evidence gap)

13. Prevention

  • Primary prevention: not applicable in the usual sense for an autosomal recessive Mendelian disorder, except via reproductive options.
  • Secondary prevention: early detection (potentially via newborn screening hydroxy‑C4 signal where implemented) and early metabolic management may reduce decompensation risk, but controlled evidence is lacking. (stiles2015successfuldiagnosisof pages 1-3, stiles2015successfuldiagnosisof pages 5-6)
  • Genetic counseling: indicated for affected families (implied by autosomal recessive inheritance and pedigree studies). (stiles2015successfuldiagnosisof pages 3-5, kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 3-3)

14. Other species / natural disease

No naturally occurring veterinary HIBCH deficiency reports were identified in the retrieved evidence set. (evidence gap)

15. Model organisms

No HIBCH-deficiency-specific animal models or iPSC models were identified in the retrieved evidence for this run. (evidence gap)

Structured evidence table (for knowledge base entry)

Disease / synonym field Summary
Preferred disease name 3-hydroxyisobutyryl-CoA hydrolase deficiency
Common synonyms HIBCH deficiency; HIBCHD; 3-hydroxy-isobutyryl-CoA hydrolase deficiency; Leigh/Leigh-like syndrome due to HIBCH deficiency (stiles2015successfuldiagnosisof pages 1-3, jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, wang2021cinicalmetabolicand pages 1-2)
OMIM disease ID OMIM #250620 (reported across cohort/case-series literature) (stiles2015successfuldiagnosisof pages 1-3, jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 1-2, alayed2020metabolicacidosisand pages 2-3)
Causal gene HIBCH; gene OMIM reported as 610690 in the Bahrain cohort (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3)
Inheritance Autosomal recessive; biallelic pathogenic variants confirmed in reported families and cohorts (stiles2015successfuldiagnosisof pages 1-3, stiles2015successfuldiagnosisof pages 3-5, kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 1-2, alayed2020metabolicacidosisand pages 2-3)
Core biochemical pathway Mitochondrial valine catabolism; HIBCH catalyzes the conversion of 3-hydroxyisobutyryl-CoA to 3-hydroxyisobutyric acid / the fifth step of valine catabolism (wang2021cinicalmetabolicand pages 1-2, marti‐sanchez2021delineatingtheneurological pages 3-5)
Pathophysiologic consequence Accumulation of 3-hydroxyisobutyryl-CoA and reactive valine-derived intermediates (including methacrylyl-CoA-related species), contributing to secondary pyruvate dehydrogenase and respiratory-chain dysfunction / Leigh-like disease (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, stiles2015successfuldiagnosisof pages 6-8)
Key blood biomarker Elevated hydroxy-C4 / C4-OH acylcarnitine (3-hydroxyisobutyryl-carnitine signal); detectable in dried blood spots and sometimes plasma, but can be normal in milder cases (stiles2015successfuldiagnosisof pages 1-3, wang2021cinicalmetabolicand pages 1-2, kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 1-2, stiles2015successfuldiagnosisof pages 5-6)
Key urine biomarkers 2,3-dihydroxy-2-methylbutyrate; S-(2-carboxypropyl)cysteine (SCPC); S-(2-carboxypropyl)cysteamine (SCPCM); some reports also note valine-pathway organic acids and variable 3-hydroxy-isovaleric acid elevations (stiles2015successfuldiagnosisof pages 1-3, wang2021cinicalmetabolicand pages 1-2, kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 3-3, baldo2024acomprehensiveapproach pages 2-4)
Typical neuroimaging Bilateral symmetric basal ganglia lesions, especially globus pallidus T2 hyperintensity; Leigh/Leigh-like pattern; white-matter changes may occur; cavitation/small cysts in pallidum/putamen reported; some long-term follow-up shows progressive cerebellar atrophy (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, marti‐sanchez2021delineatingtheneurological pages 3-5, marti‐sanchez2021delineatingtheneurological pages 7-8, taura2023leighlikesyndromewith pages 1-2, taura2023leighlikesyndromewith pages 3-4)
Typical age of onset Usually infancy / early childhood; onset reported from 6 weeks to 6 months in one cohort, median 13 months (range 8–18 months) in another; developmental delay/regression commonly begins in the first 2 years of life (jishi2024characterizationof3hydroxyisobutyrylcoa pages 4-6, wang2021cinicalmetabolicand pages 1-2)
Core clinical picture Developmental delay or regression, hypotonia, encephalopathy/acute decompensation, feeding difficulties, dystonia/spasticity/ataxia; seizures and ocular abnormalities may occur; phenotype overlaps Leigh syndrome spectrum (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, wang2021cinicalmetabolicand pages 1-2, marti‐sanchez2021delineatingtheneurological pages 7-8)
Epidemiology / rarity Ultra-rare. One study citing OMIM reported estimated frequency about 1 in 127,939 in East Asians and 1 in 551,545 in Europeans; earlier work suggested incidence may be around 1 in 130,000 and underdiagnosed (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, wang2021cinicalmetabolicand pages 1-2)
Newborn screening relevance Retrospective newborn screening card analysis showed elevated hydroxy-C4 in affected siblings, supporting potential detectability by NBS if hydroxy-C4 is assessed (stiles2015successfuldiagnosisof pages 1-3, stiles2015successfuldiagnosisof pages 6-8, stiles2015successfuldiagnosisof pages 5-6)
Diagnostic approach Parallel biochemical screening (acylcarnitine + urinary organic acids) plus NGS/WES is recommended; enzymatic confirmation in fibroblasts/tissues is possible but less routinely available (stiles2015successfuldiagnosisof pages 1-3, wang2021cinicalmetabolicand pages 1-2, baldo2024acomprehensiveapproach pages 2-4, stiles2015successfuldiagnosisof pages 5-6)
Best recent cohort / case-series references Al jishi et al., 2024 retrospective Bahrain cohort, 8 patients, DOI/URL: https://doi.org/10.24911/jbcgenetics.183-1722167696 (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, jishi2024characterizationof3hydroxyisobutyrylcoa pages 4-6)
Baldo et al., 2024 Leigh syndrome spectrum diagnostic framework; emphasizes parallel biochemical testing and notes HIBCH as a treatable valine-metabolism cause, URL: https://doi.org/10.3390/diagnostics14192133 (baldo2024acomprehensiveapproach pages 2-4, baldo2024acomprehensiveapproach pages 1-2)
Wang et al., 2021 clinical/metabolic/genetic follow-up of 8 HIBCH patients, URL: https://doi.org/10.3389/fphar.2021.605803 (wang2021cinicalmetabolicand pages 1-2)
Marti-Sanchez et al., 2021 neurological phenotype/natural history across HIBCH and ECHS1 defects; survival and imaging comparisons, URL: https://doi.org/10.1002/jimd.12288 (marti‐sanchez2021delineatingtheneurological pages 3-5, marti‐sanchez2021delineatingtheneurological pages 1-3, marti‐sanchez2021delineatingtheneurological pages 7-8)
Taura et al., 2023 case report expanding imaging spectrum to progressive cerebellar atrophy, URL: https://doi.org/10.1038/s41439-023-00251-y (taura2023leighlikesyndromewith pages 1-2, taura2023leighlikesyndromewith pages 2-3, taura2023leighlikesyndromewith pages 3-4)
Stiles et al., 2015 seminal diagnostic/NBS paper on two siblings, URL: https://doi.org/10.1016/j.ymgme.2015.05.008 (stiles2015successfuldiagnosisof pages 1-3, stiles2015successfuldiagnosisof pages 6-8, stiles2015successfuldiagnosisof pages 5-6)

Table: This table summarizes the main identifiers, pathway context, biomarkers, imaging features, onset pattern, and key references for 3-hydroxyisobutyryl-CoA hydrolase deficiency. It is designed as a compact evidence-backed reference for a disease knowledge base entry.

Recent developments and authoritative perspectives (2023–2024 emphasis)

  • 2024 (Diagnostics, MDPI): A Leigh syndrome spectrum diagnostic pipeline emphasizes parallel metabolic testing and notes that biochemical workups can rapidly characterize cases and enable intervention in a subset, relevant because HIBCH deficiency is among treatable metabolic causes within LSS. URL: https://doi.org/10.3390/diagnostics14192133 (published Sep 2024). (baldo2024acomprehensiveapproach pages 2-4, baldo2024acomprehensiveapproach pages 1-2)
  • 2024 (Bahrain cohort): A retrospective cohort expands real-world phenotypic and biochemical characterization, reports a recurrent homozygous variant in their population, and provides incidence estimates (from OMIM) across ancestries. URL: https://doi.org/10.24911/jbcgenetics.183-1722167696 (published Dec 2024). (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3, jishi2024characterizationof3hydroxyisobutyrylcoa pages 4-6)
  • 2023 (Human Genome Variation): Long-term MRI follow-up in a genetically confirmed case expands the neuroradiologic spectrum to include progressive cerebellar atrophy. URL: https://doi.org/10.1038/s41439-023-00251-y (published Aug 2023). (taura2023leighlikesyndromewith pages 1-2)

Key direct abstract quotes (verbatim as captured in retrieved full text)

  • Leigh syndrome spectrum diagnostics: “basic metabolic studies are mandatory for all patients, including an L/P ratio, plasma amino acids and acylcarnitine profiles, and urinary organic acids” (baldo2024acomprehensiveapproach pages 2-4).
  • Leigh syndrome spectrum diagnostics: “characterized 80% of our cohort and promoted specific intervention in 10% of confirmed cases” (baldo2024acomprehensiveapproach pages 1-2).
  • HIBCH vs ECHS1 comparative series (biochemistry): “Elevated plasma levels of 3-hydroxyisobutyryl carnitine” (marti‐sanchez2021delineatingtheneurological pages 7-8).
  • HIBCH function statement: “HIBCH catalyses the fifth step of valine catabolism” (marti‐sanchez2021delineatingtheneurological pages 3-5).

Notable evidence gaps for knowledge base completion

  1. MONDO, Orphanet, MeSH, and ICD mappings were not retrieved in the current tool-run evidence and require direct ontology/database queries.
  2. Robust prevalence and carrier frequency statistics remain sparse; estimates exist but vary by ancestry and methodology.
  3. No controlled clinical trials; treatment evidence is largely observational.
  4. Limited published mechanistic studies directly in patient tissues; multi-omics and model organism resources appear underdeveloped in the retrieved set.

References

  1. (stiles2015successfuldiagnosisof pages 1-3): Ashlee R. Stiles, Sacha Ferdinandusse, Arnaud Besse, Vivek Appadurai, Karen B. Leydiker, E.J. Cambray-Forker, Penelope E. Bonnen, and Jose E. Abdenur. Successful diagnosis of hibch deficiency from exome sequencing and positive retrospective analysis of newborn screening cards in two siblings presenting with leigh's disease. Molecular Genetics and Metabolism, 115(4):161-167, Aug 2015. URL: https://doi.org/10.1016/j.ymgme.2015.05.008, doi:10.1016/j.ymgme.2015.05.008. This article has 48 citations and is from a peer-reviewed journal.

  2. (wang2021cinicalmetabolicand pages 1-2): Junling Wang, Zhimei Liu, Manting Xu, Xiaodi Han, Changhong Ren, Xinying Yang, Chunhua Zhang, and Fang Fang. Cinical, metabolic, and genetic analysis and follow-up of eight patients with hibch mutations presenting with leigh/leigh-like syndrome. Frontiers in Pharmacology, Mar 2021. URL: https://doi.org/10.3389/fphar.2021.605803, doi:10.3389/fphar.2021.605803. This article has 23 citations.

  3. (marti‐sanchez2021delineatingtheneurological pages 7-8): Laura Marti‐Sanchez, Heidy Baide‐Mairena, Anna Marcé‐Grau, Roser Pons, Anastasia Skouma, Eduardo López‐Laso, Maria Sigatullina, Cristiano Rizzo, Michela Semeraro, Diego Martinelli, Rosalba Carrozzo, Carlo Dionisi‐Vici, Luis González‐Gutiérrez‐Solana, Marta Correa‐Vela, Juan Dario Ortigoza‐Escobar, Ángel Sánchez‐Montañez, Élida Vazquez, Ignacio Delgado, Sergio Aguilera‐Albesa, María Eugenia Yoldi, Antonia Ribes, Frederic Tort, Luca Pollini, Serena Galosi, Vincenzo Leuzzi, Manuela Tolve, Laura Pérez‐Gay, Luis Aldamiz‐Echevarría, Mireia Del Toro, Antonio Arranz, Filip Roelens, Roser Urreizti, Rafael Artuch, Alfons Macaya, and Belén Pérez‐Dueñas. Delineating the neurological phenotype in children with defects in the echs1 or hibch gene. Aug 2021. URL: https://doi.org/10.1002/jimd.12288, doi:10.1002/jimd.12288. This article has 48 citations and is from a peer-reviewed journal.

  4. (baldo2024acomprehensiveapproach pages 2-4): Manuela Schubert Baldo, Luísa Azevedo, Margarida Paiva Coelho, Esmeralda Martins, and Laura Vilarinho. A comprehensive approach to the diagnosis of leigh syndrome spectrum. Diagnostics, 14:2133, Sep 2024. URL: https://doi.org/10.3390/diagnostics14192133, doi:10.3390/diagnostics14192133. This article has 2 citations.

  5. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 1-3): Emtithal Al jishi, Zahra Al sahlawi, Huda Omran, Mohammed S. Almaliki, Faten Al mahroos, and Heba Alkoheji. Characterization of 3-hydroxyisobutyryl-coa hydrolase (hibch) deficiency in bahrain: a retrospective cohort study. Journal of Biochemical and Clinical Genetics, 7:068-074, Dec 2024. URL: https://doi.org/10.24911/jbcgenetics.183-1722167696, doi:10.24911/jbcgenetics.183-1722167696. This article has 0 citations.

  6. (kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 1-2): Mustafa Kılıç and Fatma Kurt-Çolak. 3-hydroxyisobutyryl-coa hydrolase deficiency in a turkish child with a novel hibch gene mutation and literature review. Molecular Syndromology, 11:170-175, Jun 2020. URL: https://doi.org/10.1159/000508728, doi:10.1159/000508728. This article has 2 citations and is from a peer-reviewed journal.

  7. (alayed2020metabolicacidosisand pages 2-3): Alaa M Alayed, Eissa Ali Faqeih, Abdulwahed Aldehaimi, Roy W A Peake, and and Naif A M Almontashiri. Metabolic acidosis and hypoglycemia in a child with leigh-like phenotype. Clinical chemistry, 66 5:739-741, May 2020. URL: https://doi.org/10.1093/clinchem/hvaa079, doi:10.1093/clinchem/hvaa079. This article has 1 citations and is from a highest quality peer-reviewed journal.

  8. (taura2023leighlikesyndromewith pages 1-2): Yoshihiro Taura, Takenori Tozawa, Kenichi Isoda, Satori Hirai, Tomohiro Chiyonobu, Naoko Yano, Takahiro Hayashi, Takeshi Yoshida, and Tomoko Iehara. Leigh-like syndrome with progressive cerebellar atrophy caused by novel hibch variants. Human Genome Variation, Aug 2023. URL: https://doi.org/10.1038/s41439-023-00251-y, doi:10.1038/s41439-023-00251-y. This article has 8 citations.

  9. (marti‐sanchez2021delineatingtheneurological pages 3-5): Laura Marti‐Sanchez, Heidy Baide‐Mairena, Anna Marcé‐Grau, Roser Pons, Anastasia Skouma, Eduardo López‐Laso, Maria Sigatullina, Cristiano Rizzo, Michela Semeraro, Diego Martinelli, Rosalba Carrozzo, Carlo Dionisi‐Vici, Luis González‐Gutiérrez‐Solana, Marta Correa‐Vela, Juan Dario Ortigoza‐Escobar, Ángel Sánchez‐Montañez, Élida Vazquez, Ignacio Delgado, Sergio Aguilera‐Albesa, María Eugenia Yoldi, Antonia Ribes, Frederic Tort, Luca Pollini, Serena Galosi, Vincenzo Leuzzi, Manuela Tolve, Laura Pérez‐Gay, Luis Aldamiz‐Echevarría, Mireia Del Toro, Antonio Arranz, Filip Roelens, Roser Urreizti, Rafael Artuch, Alfons Macaya, and Belén Pérez‐Dueñas. Delineating the neurological phenotype in children with defects in the echs1 or hibch gene. Aug 2021. URL: https://doi.org/10.1002/jimd.12288, doi:10.1002/jimd.12288. This article has 48 citations and is from a peer-reviewed journal.

  10. (stiles2015successfuldiagnosisof pages 6-8): Ashlee R. Stiles, Sacha Ferdinandusse, Arnaud Besse, Vivek Appadurai, Karen B. Leydiker, E.J. Cambray-Forker, Penelope E. Bonnen, and Jose E. Abdenur. Successful diagnosis of hibch deficiency from exome sequencing and positive retrospective analysis of newborn screening cards in two siblings presenting with leigh's disease. Molecular Genetics and Metabolism, 115(4):161-167, Aug 2015. URL: https://doi.org/10.1016/j.ymgme.2015.05.008, doi:10.1016/j.ymgme.2015.05.008. This article has 48 citations and is from a peer-reviewed journal.

  11. (stiles2015successfuldiagnosisof pages 3-5): Ashlee R. Stiles, Sacha Ferdinandusse, Arnaud Besse, Vivek Appadurai, Karen B. Leydiker, E.J. Cambray-Forker, Penelope E. Bonnen, and Jose E. Abdenur. Successful diagnosis of hibch deficiency from exome sequencing and positive retrospective analysis of newborn screening cards in two siblings presenting with leigh's disease. Molecular Genetics and Metabolism, 115(4):161-167, Aug 2015. URL: https://doi.org/10.1016/j.ymgme.2015.05.008, doi:10.1016/j.ymgme.2015.05.008. This article has 48 citations and is from a peer-reviewed journal.

  12. (kılıc20203hydroxyisobutyrylcoahydrolasedeficiency pages 3-3): Mustafa Kılıç and Fatma Kurt-Çolak. 3-hydroxyisobutyryl-coa hydrolase deficiency in a turkish child with a novel hibch gene mutation and literature review. Molecular Syndromology, 11:170-175, Jun 2020. URL: https://doi.org/10.1159/000508728, doi:10.1159/000508728. This article has 2 citations and is from a peer-reviewed journal.

  13. (jishi2024characterizationof3hydroxyisobutyrylcoa pages 4-6): Emtithal Al jishi, Zahra Al sahlawi, Huda Omran, Mohammed S. Almaliki, Faten Al mahroos, and Heba Alkoheji. Characterization of 3-hydroxyisobutyryl-coa hydrolase (hibch) deficiency in bahrain: a retrospective cohort study. Journal of Biochemical and Clinical Genetics, 7:068-074, Dec 2024. URL: https://doi.org/10.24911/jbcgenetics.183-1722167696, doi:10.24911/jbcgenetics.183-1722167696. This article has 0 citations.

  14. (taura2023leighlikesyndromewith pages 2-3): Yoshihiro Taura, Takenori Tozawa, Kenichi Isoda, Satori Hirai, Tomohiro Chiyonobu, Naoko Yano, Takahiro Hayashi, Takeshi Yoshida, and Tomoko Iehara. Leigh-like syndrome with progressive cerebellar atrophy caused by novel hibch variants. Human Genome Variation, Aug 2023. URL: https://doi.org/10.1038/s41439-023-00251-y, doi:10.1038/s41439-023-00251-y. This article has 8 citations.

  15. (stiles2015successfuldiagnosisof pages 5-6): Ashlee R. Stiles, Sacha Ferdinandusse, Arnaud Besse, Vivek Appadurai, Karen B. Leydiker, E.J. Cambray-Forker, Penelope E. Bonnen, and Jose E. Abdenur. Successful diagnosis of hibch deficiency from exome sequencing and positive retrospective analysis of newborn screening cards in two siblings presenting with leigh's disease. Molecular Genetics and Metabolism, 115(4):161-167, Aug 2015. URL: https://doi.org/10.1016/j.ymgme.2015.05.008, doi:10.1016/j.ymgme.2015.05.008. This article has 48 citations and is from a peer-reviewed journal.

  16. (baldo2024acomprehensiveapproach pages 1-2): Manuela Schubert Baldo, Luísa Azevedo, Margarida Paiva Coelho, Esmeralda Martins, and Laura Vilarinho. A comprehensive approach to the diagnosis of leigh syndrome spectrum. Diagnostics, 14:2133, Sep 2024. URL: https://doi.org/10.3390/diagnostics14192133, doi:10.3390/diagnostics14192133. This article has 2 citations.

  17. (marti‐sanchez2021delineatingtheneurological pages 11-13): Laura Marti‐Sanchez, Heidy Baide‐Mairena, Anna Marcé‐Grau, Roser Pons, Anastasia Skouma, Eduardo López‐Laso, Maria Sigatullina, Cristiano Rizzo, Michela Semeraro, Diego Martinelli, Rosalba Carrozzo, Carlo Dionisi‐Vici, Luis González‐Gutiérrez‐Solana, Marta Correa‐Vela, Juan Dario Ortigoza‐Escobar, Ángel Sánchez‐Montañez, Élida Vazquez, Ignacio Delgado, Sergio Aguilera‐Albesa, María Eugenia Yoldi, Antonia Ribes, Frederic Tort, Luca Pollini, Serena Galosi, Vincenzo Leuzzi, Manuela Tolve, Laura Pérez‐Gay, Luis Aldamiz‐Echevarría, Mireia Del Toro, Antonio Arranz, Filip Roelens, Roser Urreizti, Rafael Artuch, Alfons Macaya, and Belén Pérez‐Dueñas. Delineating the neurological phenotype in children with defects in the echs1 or hibch gene. Aug 2021. URL: https://doi.org/10.1002/jimd.12288, doi:10.1002/jimd.12288. This article has 48 citations and is from a peer-reviewed journal.

  18. (taura2023leighlikesyndromewith pages 3-4): Yoshihiro Taura, Takenori Tozawa, Kenichi Isoda, Satori Hirai, Tomohiro Chiyonobu, Naoko Yano, Takahiro Hayashi, Takeshi Yoshida, and Tomoko Iehara. Leigh-like syndrome with progressive cerebellar atrophy caused by novel hibch variants. Human Genome Variation, Aug 2023. URL: https://doi.org/10.1038/s41439-023-00251-y, doi:10.1038/s41439-023-00251-y. This article has 8 citations.

  19. (marti‐sanchez2021delineatingtheneurological pages 1-3): Laura Marti‐Sanchez, Heidy Baide‐Mairena, Anna Marcé‐Grau, Roser Pons, Anastasia Skouma, Eduardo López‐Laso, Maria Sigatullina, Cristiano Rizzo, Michela Semeraro, Diego Martinelli, Rosalba Carrozzo, Carlo Dionisi‐Vici, Luis González‐Gutiérrez‐Solana, Marta Correa‐Vela, Juan Dario Ortigoza‐Escobar, Ángel Sánchez‐Montañez, Élida Vazquez, Ignacio Delgado, Sergio Aguilera‐Albesa, María Eugenia Yoldi, Antonia Ribes, Frederic Tort, Luca Pollini, Serena Galosi, Vincenzo Leuzzi, Manuela Tolve, Laura Pérez‐Gay, Luis Aldamiz‐Echevarría, Mireia Del Toro, Antonio Arranz, Filip Roelens, Roser Urreizti, Rafael Artuch, Alfons Macaya, and Belén Pérez‐Dueñas. Delineating the neurological phenotype in children with defects in the echs1 or hibch gene. Aug 2021. URL: https://doi.org/10.1002/jimd.12288, doi:10.1002/jimd.12288. This article has 48 citations and is from a peer-reviewed journal.

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